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 A380914 #8 Feb 08 2025 10:30:06
%S A380914 1,2,11,115,1797,37621,990313,31452905,1171010809,50029903081,
%T A380914 2413119476781,129719605920565,7690829719605541,498579900892422077,
%U A380914 35086898369381747281,2663953520081549084401,217057092837921132411249,18892120969438125131207377,1749385548844357561820688853
%N A380914 E.g.f. A(x) satisfies A(x) = exp(x / (1 - x*A(x))) / (1 - x*A(x)).
%F A380914 a(n) = n! * Sum_{k=0..n} (n-k+1)^(k-1) * binomial(2*n-k,n-k)/k!.
%o A380914 (PARI) a(n, q=1, r=1, s=0, t=1, u=1) = q*n!*sum(k=0, n, (r*n+(s-r)*k+q)^(k-1)*binomial((r*u+1)*n+((s-r)*u+t-1)*k+q*u-1, n-k)/k!);
%Y A380914 Cf. A380769, A380915.
%Y A380914 Cf. A380663.
%K A380914 nonn
%O A380914 0,2
%A A380914 _Seiichi Manyama_, Feb 08 2025