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 A377716 #10 Aug 27 2025 04:25:18
%S A377716 1,2,12,116,1584,28172,619872,16289996,498428544,17417438252,
%T A377716 684759380832,29925135793676,1439467532867904,75591768584407532,
%U A377716 4303733247493423392,264082643528395550156,17375242687235713361664,1220318925238762558532012,91128522664443184593699552
%N A377716 E.g.f. satisfies A(x) = (1 + (exp(x) - 1) * A(x))^2.
%F A377716 E.g.f.: 4/(1 + sqrt(5 - 4*exp(x)))^2.
%F A377716 E.g.f.: B(x)^2, where B(x) is the e.g.f. of A052895.
%F A377716 a(n) = 2 * Sum_{k=0..n} (2*k+1)!/(k+2)! * Stirling2(n,k).
%F A377716 a(n) ~ 2^(5/2) * sqrt(5) * n^(n-1) / (exp(n) * log(5/4)^(n - 1/2)). - _Vaclav Kotesovec_, Aug 27 2025
%o A377716 (PARI) a(n) = 2*sum(k=0, n, (2*k+1)!/(k+2)!*stirling(n, k, 2));
%Y A377716 Cf. A000670, A377717.
%Y A377716 Cf. A052895, A377692.
%K A377716 nonn,changed
%O A377716 0,2
%A A377716 _Seiichi Manyama_, Nov 04 2024