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 A026231 #14 Jul 04 2021 13:44:05 %S A026231 8,17,20,26,35,44,47,53,56,62,71,74,80,89,98,101,107,116,125,128,134, %T A026231 137,143,152,155,161,164,170,179,182,188,197,206,209,215,218,224,233, %U A026231 236,242,251,260,263,269,278,287,290,296,299 %N A026231 Numbers k such that A026166(k) = A026142(k) + 1. %Y A026231 Cf. A026142, A026166. %K A026231 nonn %O A026231 1,1 %A A026231 _Clark Kimberling_ %E A026231 Title corrected by _Sean A. Irvine_, Sep 22 2019