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 A381309 #8 Feb 20 2025 08:39:58
%S A381309 1,1,1,2,9,42,209,1381,11121,96744,936337,10323865,125245457,
%T A381309 1640739336,23339285601,359236548033,5918755368865,103922094286976,
%U A381309 1941594484205793,38448924176712705,803753373207738337,17693469280066921736,409266060724837855057,9922356658347766201841
%N A381309 E.g.f. A(x) satisfies A(x) = exp( sinh(x * A(x)^(1/2)) / A(x)^(1/2) ).
%F A381309 a(n) = Sum_{k=0..n} (n/2-k/2+1)^(k-1) * A136630(n,k).
%o A381309 (PARI) a136630(n, k) = 1/(2^k*k!)*sum(j=0, k, (-1)^(k-j)*(2*j-k)^n*binomial(k, j));
%o A381309 a(n) = sum(k=0, n, (n/2-k/2+1)^(k-1)*a136630(n, k));
%Y A381309 Cf. A136630.
%K A381309 nonn
%O A381309 0,4
%A A381309 _Seiichi Manyama_, Feb 19 2025