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 A381411 #8 Feb 23 2025 08:05:28
%S A381411 1,1,1,2,21,252,2645,29248,420777,7789008,160214281,3480537568,
%T A381411 82299294077,2172147323712,63112534885725,1969853583132672,
%U A381411 65473850077772881,2323179959573426432,88007266294215935121,3540245668453458467328,150353926528453088942821
%N A381411 E.g.f. A(x) satisfies A(x) = exp( sinh(x * A(x)^2) / A(x)^2 ).
%F A381411 a(n) = Sum_{k=0..n} (2*n-2*k+1)^(k-1) * A136630(n,k).
%o A381411 (PARI) a136630(n, k) = 1/(2^k*k!)*sum(j=0, k, (-1)^(k-j)*(2*j-k)^n*binomial(k, j));
%o A381411 a(n) = sum(k=0, n, (2*n-2*k+1)^(k-1)*a136630(n, k));
%Y A381411 Cf. A136630.
%K A381411 nonn
%O A381411 0,4
%A A381411 _Seiichi Manyama_, Feb 23 2025