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 A384894 #12 Jun 12 2025 10:23:17 %S A384894 1,1,2,1,-4,-14,-30,12,330,1139,2226,-2288,-39646,-163742,-410900, %T A384894 -89273,5352720,31177720,114624554,234094417,-312845870,-5584935715, %U A384894 -32878240028,-127407695297,-315375599410,24759230680,6177102106748,44838273448641,220383314338200 %N A384894 G.f. A(x) satisfies A(x) = 1 + x/A(-x*A(x))^2. %F A384894 See A384899. %o A384894 (PARI) a(n, k=-1) = if(n*k==0, 0^n, (-1)^n*k*sum(j=1, n, binomial(-n+2*j+k-1, j-1)*a(n-j, 2*j)/j)); %Y A384894 Column k=1 of A384899. %Y A384894 Cf. A000108, A213094, A213095, A384895. %Y A384894 Cf. A213091. %K A384894 sign %O A384894 0,3 %A A384894 _Seiichi Manyama_, Jun 12 2025