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 A377719 #10 Nov 05 2024 08:11:31
%S A377719 1,0,4,6,128,610,12192,112154,2416416,34337538,827541200,16047333082,
%T A377719 436958019984,10718568174626,329594991463584,9737689680629850,
%U A377719 336439401299953472,11581626068262440194,446492838289046854320,17496904148975860376474,747070411957344952492080
%N A377719 E.g.f. satisfies A(x) = (1 + x * (exp(x) - 1) * A(x))^2.
%F A377719 E.g.f.: 4/(1 + sqrt(1 - 4*x*(exp(x) - 1)))^2.
%F A377719 E.g.f.: B(x)^2, where B(x) is the e.g.f. of A371142.
%F A377719 a(n) = 2 * n! * Sum_{k=0..floor(n/2)} (2*k+1)! * Stirling2(n-k,k)/( (n-k)! * (k+2)! ).
%o A377719 (PARI) a(n) = 2*n!*sum(k=0, n\2, (2*k+1)!*stirling(n-k, k, 2)/((n-k)!*(k+2)!));
%Y A377719 Cf. A371142, A377438.
%K A377719 nonn
%O A377719 0,3
%A A377719 _Seiichi Manyama_, Nov 04 2024