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 A187662 #11 Oct 19 2024 08:33:32
%S A187662 1,3,45,1340,62133,3926607,313159138,30077004204,3373855596485,
%T A187662 432604296358341,62396125789568633,9997677582465775336,
%U A187662 1761777732880595653932,338625441643226149909356,70500059235176885929427760
%N A187662 Convolution of the (signless) central Lah numbers (A187535) and the central Stirling numbers of the second kind (A007820).
%F A187662 a(n) = Sum_{k=0..n} Lah(2*k,k)*S(2*n-2*k,n-k).
%F A187662 a(n) ~ 2^(4*n) * n^n / (exp(n) * sqrt(2*Pi*n)). - _Vaclav Kotesovec_, May 21 2014
%p A187662 L := n -> if n=0 then 1 else binomial(2*n-1,n-1)*(2*n)!/n! fi;
%p A187662 seq(sum(L(k)*combinat[stirling2](2*(n-k),n-k),k=0..n),n=0..12);
%t A187662 L[n_] := If[n == 0, 1, Binomial[2n - 1, n - 1](2n)!/n!]
%t A187662 Table[Sum[L[k]StirlingS2[2n - 2k, n - k], {k, 0, n}], {n, 0, 14}]
%o A187662 (Maxima) L(n):= if n=0 then 1 else binomial(2*n-1,n-1)*(2*n)!/n!;
%o A187662 makelist(sum(L(k)*stirling2(2*n-2*k,n-k),k,0,n),n,0,12);
%Y A187662 Cf. A187535, A007820.
%K A187662 nonn,easy
%O A187662 0,2
%A A187662 _Emanuele Munarini_, Mar 12 2011