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 A009276 #16 Apr 01 2017 13:58:40
%S A009276 1,1,-1,-4,9,52,-175,-1370,5985,60216,-320063,-3929550,24549745,
%T A009276 354693796,-2543955167,-42233123938,341610526145,6404634620016,
%U A009276 -57626692351871,-1203767371104790,11918048043239377,274395314816604636
%N A009276 E..g.f. exp(tanh(x)/exp(x)).
%F A009276 a(n)=sum(m=1..n, sum(i=0..n-m, binomial(n,i+m)*(m^(n-i-m)*(sum(k=0..i+m, stirling2(i+m,k+m)*2^(i-k)*binomial(k+m-1,m-1)*(k+m)!*(-1)^(k+n-i-m)))))/m!), n>0, a(0)=1. - _Vladimir Kruchinin_, Jun 06 2011
%t A009276 Exp[ Tanh[ x ]/Exp[ x ] ]
%t A009276 CoefficientList[Series[E^(Tanh[x]/E^x), {x, 0, 20}], x] * Range[0, 20]! (* _Vaclav Kotesovec_, Jan 23 2015 *)
%o A009276 (Maxima)
%o A009276 a(n):=sum(sum(binomial(n,i+m)*(m^(n-i-m)*(sum(stirling2(i+m,k+m)*2^(i-k)*binomial(k+m-1,m-1)*(k+m)!*(-1)^(k+n-i-m),k,0,i+m))),i,0,n-m)/m!,m,1,n); /* _Vladimir Kruchinin_, Jun 06 2011 */
%K A009276 sign,easy
%O A009276 0,4
%A A009276 _R. H. Hardin_
%E A009276 Extended with signs by _Olivier Gérard_, Mar 15 1997