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 A115250 #4 Jul 31 2023 13:55:58 %S A115250 0,2,4,37,8,138,13,41,27,167,335,111,746,492,8366,3032,7223 %N A115250 Least inverse of A115247, or -1 if no inverse exists. %Y A115250 Cf. A115247. %K A115250 nonn,more %O A115250 0,2 %A A115250 _Christian G. Bower_, Jan 17 2006