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 A377740 #10 Nov 06 2024 04:37:11
%S A377740 1,3,19,199,2957,57341,1377175,39531927,1321803705,50491876825,
%T A377740 2170432191491,103726081148339,5456983990544773,313449393386822421,
%U A377740 19521567325327386831,1310428405901227674511,94325931842372734994417,7248016420075574268626225,592190617414334419733622139
%N A377740 E.g.f. satisfies A(x) = exp(x) * (1 + x * A(x))^2.
%F A377740 E.g.f.: 4*exp(x)/(1 + sqrt(1 - 4*x*exp(x)))^2.
%F A377740 a(n) = n! * Sum_{k=0..n} (k+1)^(n-k-1) * binomial(2*k+2,k)/(n-k)!.
%F A377740 a(n) = A295238(n+1)/(n+1).
%o A377740 (PARI) a(n) = n!*sum(k=0, n, (k+1)^(n-k-1)*binomial(2*k+2, k)/(n-k)!);
%Y A377740 Cf. A072597, A377741.
%Y A377740 Cf. A295238, A377574.
%K A377740 nonn
%O A377740 0,2
%A A377740 _Seiichi Manyama_, Nov 05 2024