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 A064456 #13 Dec 16 2019 01:57:15 %S A064456 1,3,79,235,431,1503,2943,6059,6619,18911,54223,302467995,1772665631, %T A064456 2148845167,5145362667,129465909327,212089391807 %N A064456 A064434(n) = 0. %C A064456 a(18) > 4*10^12. - _Donovan Johnson_, Jan 19 2011 %C A064456 Also indices n where A079878(n)=1. - _R. J. Mathar_, Nov 13 2011 %o A064456 (ARIBAS): a := 0; for n := 1 to 3000000000 do am := a; a := (am*2 + 1) mod n; if a = 0 then write(n," "); end; end; %Y A064456 Cf. A064433. %K A064456 nonn,more %O A064456 1,2 %A A064456 Jonathan Ayres (JonathanAyres(AT)btinternet.com), Oct 01 2001 %E A064456 More terms from _Klaus Brockhaus_, Oct 04 2001 %E A064456 Offset corrected and a(15)-a(17) from _Donovan Johnson_, Jan 19 2011