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 A381260 #8 Feb 18 2025 08:57:17
%S A381260 1,1,5,52,789,16116,415633,12963952,474761577,19974663568,
%T A381260 949570545501,50341473508800,2944936306028797,188445333393978688,
%U A381260 13094108333345047401,981850811606401705216,79025876659261666454481,6795576727642475440025856,621789675800920271144983477
%N A381260 Expansion of e.g.f. exp( -LambertW(-2 * x * cosh(x)) / 2 ).
%C A381260 As stated in the comment of A185951, A185951(n,0) = 0^n.
%F A381260 E.g.f. A(x) satisfies A(x) = exp( x * cosh(x) * A(x)^2 ).
%F A381260 a(n) = Sum_{k=0..n} (2*k+1)^(k-1) * A185951(n,k).
%o A381260 (PARI) a185951(n, k) = binomial(n, k)/2^k*sum(j=0, k, (2*j-k)^(n-k)*binomial(k, j));
%o A381260 a(n) = sum(k=0, n, (2*k+1)^(k-1)*a185951(n, k));
%Y A381260 Cf. A185951, A381140.
%K A381260 nonn
%O A381260 0,3
%A A381260 _Seiichi Manyama_, Feb 18 2025