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 A103963 #11 Dec 20 2018 12:43:54
%S A103963 2,3,4,7,12,23,25,2551,800516
%N A103963 Record values in A040081.
%C A103963 A040081(659) not yet found. The index sequence of this one is 1, 13, 23, 43, 59, 88, 127, 148, 659.
%C A103963 800516 was found by Dave Linton in 2004.
%H A103963 Ray Ballinger and Wilfrid Keller, <a href="http://www.prothsearch.com/rieselprob.html">Riesel Problem</a>
%e A103963 A040081(1)=2; A040081(13)=3; A040081(659)>8192
%t A103963 kmax=8192; k = 0; n = 0; km = k; While[k < kmax, n++; k = 0; cp = n*(2^k) - 1; While[(!PrimeQ[cp]) && (k < kmax), k++; cp = n*(2^k) - 1]; If[k > km, km = k; Print[{n, km}]]]
%Y A103963 Cf. A038699, A040081, A240113.
%K A103963 nonn,more
%O A103963 1,1
%A A103963 _Lei Zhou_, Feb 24 2005
%E A103963 Edited by _T. D. Noe_, Nov 15 2010