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 A380717 #9 Jan 31 2025 09:25:49
%S A380717 1,2,13,151,2561,57401,1602985,53659453,2095244289,93523526065,
%T A380717 4698386208521,262397580544133,16128832249562785,1082120615743840297,
%U A380717 78695060375718726633,6166431270471329586301,517970728078392717716225,46432097598077316120950369,4424506354750061857673476873
%N A380717 E.g.f. A(x) satisfies A(x) = exp(x * A(x)^2 * (1 - x*A(x))^2) / (1 - x*A(x)).
%F A380717 a(n) = n! * Sum_{k=0..n} (n+k+1)^(k-1) * binomial(2*n-2*k,n-k)/k!.
%o A380717 (PARI) a(n) = n!*sum(k=0, n, (n+k+1)^(k-1)*binomial(2*n-2*k, n-k)/k!);
%Y A380717 Cf. A194471, A380673.
%K A380717 nonn
%O A380717 0,2
%A A380717 _Seiichi Manyama_, Jan 30 2025