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 A385013 #12 Jun 15 2025 09:57:16 %S A385013 1,1,2,4,9,19,37,52,-25,-630,-3616,-15897,-61476,-215135,-677464, %T A385013 -1823081,-3389900,2523349,73121734,526205851,2914005085,14163375846, %U A385013 62788424920,255900158756,945473736954,3008738746058,6827204137454,-2853842162077,-171206510083289 %N A385013 G.f. A(x) satisfies A(x) = 1 + x*A(x)/A(-x*A(x)^2). %F A385013 See A385017. %o A385013 (PARI) a(n, k=-1) = if(n*k==0, 0^n, (-1)^n*k*sum(j=1, n, binomial(-2*n+2*j+k-1, j-1)*a(n-j, j)/j)); %Y A385013 Column k=1 of A385017. %Y A385013 Cf. A000108, A213225, A213226, A384951. %Y A385013 Cf. A213091. %K A385013 sign %O A385013 0,3 %A A385013 _Seiichi Manyama_, Jun 15 2025