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 A080527 #13 Mar 10 2022 11:24:10
%S A080527 1,3,30,543,14745,546618,26119965,1547467743,110507211390,
%T A080527 9310580616243,910032696123645,101790848712790218,
%U A080527 12883623878563854105,1827803943114479006043,288318381606931126782270,50215020818975432279332743,9597691024295026236008687265
%N A080527 Expansion of e.g.f. exp(3*cosh(x))/e^3 (even powers only).
%C A080527 Periodic zeros suppressed.
%F A080527 E.g.f.: exp(3*cosh(x)-3).
%F A080527 a(0) = 1; a(n) = 3 * Sum_{k=1..n} binomial(2*n-1,2*k-1) * a(n-k). - _Ilya Gutkovskiy_, Mar 10 2022
%e A080527 exp(3*cosh(x))/exp(3) = 1 + 3*x^2/2! + 30*x^4/4! + ...
%t A080527 With[{nn=30},Take[CoefficientList[Series[Exp[3Cosh[x]]/E^3,{x,0,nn}],x] Range[0,nn]!,{1,-1,2}]] (* _Harvey P. Dale_, Dec 15 2013 *)
%Y A080527 Cf. A000807, A005046, A081565.
%K A080527 easy,nonn
%O A080527 0,2
%A A080527 _Paul Barry_, Mar 22 2003