The smallest known Bi-twin chain of length k
 k  n = 0 → base twin prime n's  Digits  When Discoverer
1 4 • 2n ± 1 0 1 - -
2 6 • 2n ± 1 0,1 1 - -
3 1005 • 7# • 2n ± 1 0..2 6 Sep 1998 Henri Lifchitz
4 1208 • 7# • 2n ± 1 0..3 6+ Sep 1998 Henri Lifchitz
5 1394847 • 13# • 2n ± 1 0..4 11+ Dec 1998 Jack Brennen
6 2456506542 • 13# • 2n ± 1 0..5 14+ Dec 1998 Jack Brennen
7 11228462199623 • 13# • 2n ± 1 0..6 18+ Oct 1999 Paul Jobling
8 21033215071024191 • 13# • 2n ± 1 0..7 21+ Feb 2002 Paul Jobling, Phil Carmody
9 3746642772919829270 • 13# • 2n ± 1 0..8 24+ Dec 2008 Jaroslaw Wroblewski

The largest known Bi-twin chain of length k
 k  n = 0 → base twin prime n's   Digits   When Discoverer History
1 2996863034895 • 21290000 • 2n ± 1 0 388342 19 Sep 2016 Tom Greer, PrimeGrid -
2 235729239034 • 2n ± 1 0,1 2971+ Jun 2017 Oscar Östlin
3 204035674219 • 1609# • 2n ± 1 0..2 695 Jul 2016 Didier Boivin
4 9185178409925 • 487# • 2n ± 1 0..3 214+ Feb 2017 Didier Boivin
5 144941178918272079102115840 • 307# • 2n ± 1 0..4 149+ Apr 2015 Andrey Balyakin
6 13606766452766743612170760770604800569607499673427359309449867203199910424562265741688607604736 • 61# • 2n ± 1 0..5 118+ Apr 2014 Primecoin
7 149203764794818055927424 • 73# • 2n ± 1 0..6 52+ Apr 2015 Andrey Balyakin
8 10739718035045524715 • 13# • 2n ± 1 0..7 24+ Dec 2008 Jaroslaw Wroblewski
9 3746642772919829270 • 13# • 2n ± 1 0..8 24+ Dec 2008 Jaroslaw Wroblewski