3x+1 Class records calculation progress map
Status of the 3x+1 class record progress as of: May 19, 2023.
Intervals are indicated in units of 1,000,000,000,000 (1 E+12 or 1 trillion numbers).
Calculation of a single block of 10,000 units takes approximately 5-10 days on an NVIDIA graphics processor.

All class records found so far can be viewed on the class records page.
This project can only run because of many cooperating contributors.
If you would like to contribute one or more blocks please go to the search page.
Note : the 3x+1 problem is just one of many distributed projects on the internet. 		Trajectory of 63,728,127
Progress history
May 18 2023 : All blocks up to 21,000 completed. Three more class record confirmed.
April 30 2023 : All blocks up to 19,940 completed. One more class record confirmed.
March 22 2023 : All blocks up to 19,860 completed. Five class records confirmed.
January 23 2023 : All blocks up to 18,500 completed. Every number up to 64 bits checked. Two class records confirmed.
January 8 2023 : All blocks up to 17,700 completed. Three class records confirmed.
August 29 2022 : All blocks up to 16,400 completed. Four class records confirmed.
June 30 2022 : All blocks up to 15,140 completed. One more class record confirmed.
May 22 2022 : All blocks up to 15,000 completed. Delay record 2442 and six more class record confirmed.
May 7 2022 : Possible Delay record (Delay 2442) found by Kevin.
March 30 2022 : All blocks up to 13,480 completed. Delay record 2429 and four more class record confirmed.
February 10 2022 : Possible new Delay record (Delay 2429) found by Kevin.
January 31 2022 : All blocks up to 12,300 completed. Six more class records confirmed.
Show/Hide earlier milestones
December 2021 : All blocks up to 10,820 completed. Eight class records confirmed.
September 2021 : New Delay record (Delay 2426) found by Kevin.
August 2021 : All blocks up to 9000,000 completed. Six class records confirmed.
July 2021 : All blocks up to 8000,000 completed. Eight class records confirmed.
May 2021 : All blocks up to 6640,000 completed. Twelve class records confirmed.
April 2021 : New Delay record (Delay 2389) found by Kevin.
February 2021 : New Delay record (Delay 2363) found by Kevin.
February 2021 : New Delay record (Delay 2337) found by Volkmar.
January 2021 : All blocks up to 4700,000 completed. Eight class records confirmed.
December 2020 : All blocks up to 3940,000 completed. Delay record 2334 and ten more class records confirmed.
December 15 2020 : New Delay record (Delay 2334) found by Kevin.
November 2020 : All blocks up to 2900,000 completed. Delay record 2331 and twelve more class records confirmed
September 2020 : All blocks up to 2300,000 completed. Eleven more class records confirmed
September 2020 : All blocks up to 2000,000 completed. Fifteen more class records confirmed
August 2020 : All blocks up to 1620,000 completed. Delay record 2330 and fifteen more class records confirmed
July 2020 : All blocks up to 1300,000 completed. Two Delay records (2283,2286) and 35 class records confirmed
June 30 2020 : Possible new Delay record (Delay 2330) found by Eric.
June 28 2020 : Possible new Delay record (Delay 2286) found by Kevin.
May 30 2020 : Possible new Delay record (Delay 2283) found by Kevin.
May 2020 : All blocks up to 820,000 completed. Sixteen class record confirmed. All class records below 2100 known.
March 2020 : All blocks up to 698,000 completed. Twelve more class records confirmed.
December 2019 : All blocks up to 602,000 completed. Nine class records confirmed.
September 2019 : All blocks up to 561,200 completed. Delay record 2277 and ten more class record confirmed.
May 2019 : All blocks up to 500,000 completed. Delay record 2264 and eight more class records confirmed.
March 2019 : All blocks up to 455,200 completed. Lowest missing class record (2070) and four others confirmed.
December 2018 : All blocks up to 387,000 completed. Delay record 2261 and nine more class records confirmed.
October 2018 : All blocks up to 366,400 completed. Six more class records confirmed.
June 2018 : All blocks up to 346,000 completed. Three more class records confirmed.
December 2017 : All blocks up to 326,500 completed. Five more class records confirmed.
May 2017 : All blocks up to 305,400 completed. 258 reached. Two more class record confirmed.
October 2016 : All blocks up to 280,000 completed. Delay record 2258 and two more class records confirmed.
March 2016 : All blocks up to 275,200 completed. Four more class records confirmed.
March 19 2016 : Possible new Delay Record (Delay 2258) found by Lutz.
December 2015 : All blocks up to 263,350 completed. Four more class records confirmed. 2100 class records known.
July 2015 : All blocks up to 245,500 completed. Five more class records confirmed.
December 2014 : All blocks up to 222,280 completed. Three more class records confirmed.
November 2014 : All blocks up to 213,800 completed. Delay record 2255 and two more class records confirmed.
May 2014 : All blocks up to 203,920 completed. Three class records confirmed.
February 2014 : All blocks up to 194,060 completed. Five class records confirmed. All class records up to 2050 known.
November 2013 : All blocks up to 184,000 completed. Three more class records confirmed
June 2013 : All blocks up to 166,700 completed. Two more class records confirmed.
April 2013 : All blocks up to 165,200 completed. One more class record confirmed.
February 2013 : All blocks up to 160,740 completed. Six more class records confirmed.
November 2012 : All blocks up to 148,800 completed. Five more class records confirmed
May 2012 : All blocks up to 132,360 completed. Five class records confirmed.
January 2012 : All blocks up to 121,500 completed. Final missing class record below 2000 found.
December 2011 : All blocks up to 120,200 completed. One class record confirmed.
October 2011 : All blocks up to 117,000 completed. Three more class record confirmed.
July 2011 : All blocks up to 107,500 completed. Delay record 2254 and three class records confirmed.
April 2011 : All blocks up to 97,080 completed. Delay Record 2091 and two other class records confirmed.
November 2010 : All blocks up to 91,880 completed. Three class records confirmed.
August 2010 : All blocks up to 90,000 completed. Four more class records confirmed.
February 2010 : All blocks up to 82,700 completed. Two class records confirmed.
June 2009 : All blocks up to 76,160 completed. The lowest missing CR (1964) and one other confirmed.
April 2009 : All blocks up to 72,520 completed, passing 256. Three class records confirmed.
February 2009 : All blocks up to 71,020 completed. One more class record confirmed.
December 2008 : All blocks up to 69,740 completed. The lowest missing CR (1951) and two more confirmed.
November 2008 : All blocks up to 67,500 completed. Class record 2000 finally confirmed.
October 2008 : All blocks up to 66,380 completed. Four more class records confirmed.
May 2008 : All blocks up to 61,160 completed. The lowest missing CR (1925) and three others confirmed.
December 2007 : All blocks up to 58,600 completed. Four class records confirmed.
April 2007 : All blocks up to 54,540 completed. Five more class records confirmed.
October 2006 : All blocks up to 50,000 completed. Delay Record 2090 and five class records confirmed.
November 2005 : All blocks up to 46,100 completed. Double of Record 2045 confirmed as Delay Record 2046.
August 2005 : All blocks up to 45,040 completed. Five class records confirmed.
May 2005 : Delay Record of 2090 found at ±46,785 E+12 by Eric
February 2005 : All blocks up to 42,060 completed. Three more class record confirmed.
November 2004 : All blocks up to 40,000 completed. Four class records confirmed.
August 2004 : All blocks up to 37,500 completed. Another four class records confirmed.
May 2004 : All blocks up to 36,120 completed. Seven class records confirmed.
January 2004 : All blocks up to 31,960 completed. Five further class records confirmed.
November 2003 : All blocks up to 29,840 completed. One more class record confirmed.
August 2003 : All blocks up to 29,240 completed. Another fifteen class records confirmed.
April 2003 : All blocks up to 23,100 completed. Delay record 2045 and seven class records confirmed.
December 2002 : All blocks up to 20,100 completed. All class records below 1900 known.
November 2002 : All blocks up to 20,000 completed. Delay record 2042 and fourteen class records confirmed.
November 2002 : Delay Record of 2045 found at ±22,702 E+12 by Kevin
July 2002 : All blocks up to 16,460 completed. Delay record 2039 and fifteen class records confirmed.
April 2002 : All blocks up to 12,720 completed. Another fourteen class records confirmed.
March 2002 : Delay Record of 2042 found at ±17,026 E+12 by Michael
February 2002 : All blocks up to 9340 completed. Two more class records confirmed.
December 2001 : Delay Record of 2039 found at ±12,770 E+12 by Billy
November 2001 : All blocks up to 9020 completed. One Delay record and ten class records confirmed.
September 2001 : All blocks up to 6800 completed. Three Delay records and fourteen class records confirmed. 
August 2001 : All blocks up to 3600 completed. Two Delay records and five class records confirmed
June 2001 : Delay Record of 1958 found at ±7579 E+12 by Kevin
May 2001 : Delay Record of 1919 found at ±6482 E+12 by Kevin
April 2001 : Delay Record of 1916 found at ±4861 E+12 by Kevin
March 2001 : Delay Record of 1903 found at ±4320 E+12 by Kevin
March 2001 : Delay Record of 1895 found at ±3586 E+12 by Eric
March 2001 : Delay Record of 1874 found at ±2978 E+12 by Kevin
February 2001 : All blocks up to 2620 completed. Three class records confirmed.
January 2001 : New Class and Delay Record of 1871 found at 2234,047405,400065.

Range 2000-20000
completed (view)		Range 20000-40000
completed (view)		Range 40000-60000
completed (view)		Range 60000-80000
completed (view)		Range 80000-100000
completed (view)
Range 100000-120000
completed (view)		Range 120000-140000
completed (view)		Range 140000-160000
completed (view)		Range 160000-180000
completed (view)		Range 180000-200000
completed (view)
Range 200000-300000
completed (view)		Range 300000-400000
completed (view)		Range 400000-500000
completed (view)		Range 500000-600000
completed (view)		Range 600000-700000
completed (view)
Range 700000-800000
completed (view)		Range 800000-900000
completed (view)		Range 900000-1000000
completed (view)		Range 1000000-2000000
completed (view)		Range 2000000-3000000
completed (view)
Range 3000000-4000000
completed (view)		Range 4000000-5000000
completed (view)		Range 5000000-10000000
completed (view)		Range 10000000-15000000
completed (view)		Range 15000000-20000000
completed (view)
Not yet assigned Assigned,
not yet started		 Assigned,
in progress		 Entire interval
completed		 Interval completed
class record found
20000000-10000
Kevin		 20010000-20000
Kevin		 20020000-30000
Kevin		 20030000-40000
Kevin		 20040000-50000
Kevin		 20050000-60000
Kevin		 20060000-70000
Kevin		 20070000-80000
Kevin		 20080000-90000
Kevin		 20090000-00000
Kevin
20100000-10000
Kevin		 20110000-20000
Kevin		 20120000-30000
Kevin		 20130000-40000
Kevin		 20140000-50000
Kevin		 20150000-60000
Kevin		 20160000-70000
Kevin		 20170000-80000
Kevin		 20180000-90000
Kevin		 20190000-00000
Kevin
20200000-10000
Kevin		 20210000-20000
Kevin		 20220000-30000
Kevin		 20230000-40000
Kevin		 20240000-50000
Kevin		 20250000-60000
Kevin		 20260000-70000
Kevin		 20270000-80000
Kevin		 20280000-90000
Kevin		 20290000-00000
Kevin
20300000-10000
Kevin		 20310000-20000
Kevin		 20320000-30000
Kevin		 20330000-40000
Kevin		 20340000-50000
Kevin		 20350000-60000
Kevin		 20360000-70000
Kevin		 20370000-80000
Kevin		 20380000-90000
Kevin		 20390000-00000
Kevin
20400000-10000
Kevin		 20410000-20000
Kevin		 20420000-30000
Kevin		 20430000-40000
Kevin		 20440000-50000
Kevin		 20450000-60000
Kevin		 20460000-70000
Kevin		 20470000-80000
Kevin		 20480000-90000
Kevin		 20490000-00000
Kevin
20500000-10000
Kevin		 20510000-20000
Kevin		 20520000-30000
Kevin		 20530000-40000
Kevin		 20540000-50000
Kevin		 20550000-60000
Kevin		 20560000-70000
Kevin		 20570000-80000
Kevin		 20580000-90000
Kevin		 20590000-00000
Kevin
20600000-10000
Kevin		 20610000-20000
Kevin		 20620000-30000
Kevin		 20630000-40000
Kevin		 20640000-50000
Kevin		 20650000-60000
Kevin		 20660000-70000
Kevin		 20670000-80000
Kevin		 20680000-90000
Kevin		 20690000-00000
Kevin
20700000-10000
Kevin		 20710000-20000
Kevin		 20720000-30000
Kevin		 20730000-40000
Kevin		 20740000-50000
Kevin		 20750000-60000
Kevin		 20760000-70000
Kevin		 20770000-80000
Kevin		 20780000-90000
Kevin		 20790000-00000
Kevin
20800000-10000
Kevin		 20810000-20000
Kevin		 20820000-30000
Kevin		 20830000-40000
Kevin		 20840000-50000
Kevin		 20850000-60000
Kevin		 20860000-70000
Kevin		 20870000-80000
Kevin		 20880000-90000
Kevin		 20890000-00000
Kevin
20900000-10000
Kevin		 20910000-20000
Kevin		 20920000-30000
Kevin		 20930000-40000
Kevin		 20940000-50000
Kevin		 20950000-60000
Kevin		 20960000-70000
Kevin		 20970000-80000
Kevin		 20980000-90000
Kevin		 20990000-00000
Kevin
21000000-10000
Lutz		 21010000-20000
Lutz		 21020000-30000
Luiz		 21030000-40000
Luiz		 21040000-50000
Wenjie		 21050000-60000
Wenjie		 21060000-70000
Daniel		 21070000-80000
Daniel		 21080000-90000
Eric		 21090000-00000
Eric
21100000-10000
Eric		 21110000-20000
Eric		 21120000-30000
 21130000-40000
 21140000-50000
 21150000-60000
 21160000-70000
 21170000-80000
 21180000-90000
 21190000-00000
21200000-10000
Kevin		 21210000-20000
Kevin		 21220000-30000
Kevin		 21230000-40000
Kevin		 21240000-50000
Kevin		 21250000-60000
Kevin		 21260000-70000
Kevin		 21270000-80000
Kevin		 21280000-90000
Kevin		 21290000-00000
Kevin
21300000-10000
Kevin		 21310000-20000
Kevin		 21320000-30000
Kevin		 21330000-40000
Kevin		 21340000-50000
Kevin		 21350000-60000
Kevin		 21360000-70000
Kevin		 21370000-80000
Kevin		 21380000-90000
Kevin		 21390000-00000
Kevin
21400000-10000
Kevin		 21410000-20000
Kevin		 21420000-30000
Kevin		 21430000-40000
Kevin		 21440000-50000
Kevin		 21450000-60000
Kevin		 21460000-70000
Kevin		 21470000-80000
Kevin		 21480000-90000
Kevin		 21490000-00000
Kevin
21500000-10000
Kevin		 21510000-20000
Kevin		 21520000-30000
Kevin		 21530000-40000
Kevin		 21540000-50000
Kevin		 21550000-60000
Kevin		 21560000-70000
Kevin		 21570000-80000
Kevin		 21580000-90000
Kevin		 21590000-00000
Kevin
21600000-10000
Kevin		 21610000-20000
Kevin		 21620000-30000
Kevin		 21630000-40000
Kevin		 21640000-50000
Kevin		 21650000-60000
Kevin		 21660000-70000
Kevin		 21670000-80000
Kevin		 21680000-90000
Kevin		 21690000-00000
Kevin
Contributions by
EricEric Roosendaal, Netherlands (author) LutzLutz Nebe, Germany
KevinKevin Hebb, Alberta, Canada WenjieFang Wenjie, China
LuizLuiz Antonio Souza, Brazil DanielDaniel Podobinski

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