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 A156060 #10 Dec 12 2023 08:04:26 %S A156060 0,1,1,3,5,2,3,7,4,0,8,8,6,4,7,6,2,5,0,1,1,3,5,2,3,7,4,0,8,8,6,4,7,6, %T A156060 2,5,0,1,1,3,5,2,3,7,4,0,8,8,6,4,7,6,2,5,0,1,1,3,5,2,3,7,4,0,8,8,6,4, %U A156060 7,6,2,5,0,1,1,3,5,2,3,7,4,0,8,8,6,4,7,6,2,5,0,1,1,3,5,2,3,7,4,0,8,8,6,4,7 %N A156060 Jacobsthal numbers A001045 mod 9. %C A156060 Period length 18. [Proof from A001045(n)=87381*A001045(n-17)+87382*A001045(n-18), where 87381 == 0 (mod 9) and 87382 == 1 (mod 9).] [From _R. J. Mathar_, Feb 06 2009] %Y A156060 Cf. A001045. [From _Dmitry Kamenetsky_, Feb 06 2009] %K A156060 nonn,easy %O A156060 0,4 %A A156060 _Paul Curtz_, Feb 03 2009 %E A156060 Extended by _R. J. Mathar_ and _Dmitry Kamenetsky_, Feb 06 2009