This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A064812 #9 May 07 2024 13:57:27
%S A064812 5,3,2,2131,1531,33301,16651,15514861,857095381,205528443121,
%T A064812 1389122693971,216857744866621,758083947856951,107588900851484911,
%U A064812 69257563144280941
%N A064812 Smallest prime p such that the infinite sequence {p, p'=2p-1, p''=2p'-1, ...} begins with a string of exactly n primes.
%C A064812 Chains of length n of nearly doubled primes.
%C A064812 Smallest prime beginning a complete Cunningham chain of length n of the second kind. (For the first kind see A005602.) - _Jonathan Sondow_, Oct 30 2015
%H A064812 G. Löh, <a href="http://www.jstor.org/stable/2008735">Long chains of nearly doubled primes</a>, Math. Comp., 53 (1989), 751-759.
%H A064812 Wikipedia, <a href="https://en.wikipedia.org/wiki/Cunningham_chain">Cunningham chain</a>
%e A064812 a(3) = 2 because 2 is the smallest prime such that the sequence {2, 3, 5, 9, ...} begins with exactly 3 primes, where each term in the sequence is twice the preceding term minus 1.
%Y A064812 A better version of A005603.
%Y A064812 Cf. (A005382 and A005383), A057326, A057327, A057328, A057329, A057330, A005602.
%Y A064812 Cf. A002808, A006450, A049076-A049081, A050436, A076237-A076239, A050436-A050439, A065860, A181697, A263879.
%K A064812 nonn
%O A064812 1,1
%A A064812 _David Terr_, Oct 21 2002