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 A026408 #8 Sep 27 2019 02:50:35 %S A026408 1,2,2,3,5,4,5,6,7,8,6,8,11,14,13,11,13,11,17,13,18,20,23,17,20,26,24, %T A026408 25,27,28,25,21,28,27,35,30,37,24,26,37,34,39,41,39,36,22,26,48,46,47, %U A026408 48,33,34,52,46,31,32,38,59,50,36,31,33,55,64,66,67,68,65,58,59,72,65 %N A026408 a(n) = s(k), where, at the end of stage n when forming A026409, k is the greatest integer such that s(j) > 0 for all j < k. %K A026408 nonn %O A026408 1,2 %A A026408 _Clark Kimberling_ %E A026408 More terms from _Sean A. Irvine_, Sep 26 2019