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 A217485 #11 Nov 27 2017 11:31:47
%S A217485 1,6,43,396,4565,64146,1073919,20996376,471081385,11947911966,
%T A217485 338204687315,10570101018276,361458024882045,13421571912745386,
%U A217485 537661560385125031,23108777539028187696,1060571767117824260945,51760585513634983767606
%N A217485 Convolution of the numbers in sequence A080253.
%F A217485 a(n) = sum(c(k)*c(n.k),k=0..n), where c(n) = A080253(n).
%F A217485 a(n) ~ n! * 2^(n + 1/2) / (log(2))^(n+1). - _Vaclav Kotesovec_, Nov 27 2017
%t A217485 t[n_] := Sum[StirlingS2[n, k] k!, {k, 0, n}]; c[n_] := Sum[Binomial[n, k] 2^k t[k], {k, 0, n}]; Table[Sum[c[k]c[n-k], {k,0,n}], {n,0,100}]
%o A217485 (Maxima) t(n):=sum(stirling2(n,k)*k!,k,0,n);
%o A217485 c(n):=sum(binomial(n,k)*2^k*t(k),k,0,n);
%o A217485 makelist(sum(c(k)*c(n-k),k,0,n),n,0,40);
%Y A217485 Cf. A080253, A000670, A217483, A217484, A217486, A217487, A217488.
%K A217485 nonn
%O A217485 0,2
%A A217485 _Emanuele Munarini_, Oct 04 2012