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 A336637 #4 Jul 28 2020 22:20:49
%S A336637 1,4,60,1648,71612,4448384,370135632,39480942848,5227020747708,
%T A336637 837878205997216,159457868003008640,35459969754432262208,
%U A336637 9093585253916177728592,2659611377508767798535488,878768601771275773332660736,325350340926291926090183214848
%N A336637 Sum_{n>=0} a(n) * x^n / (n!)^2 = exp(BesselI(0,2*sqrt(x))^4 - 1).
%F A336637 a(0) = 1; a(n) = (1/n) * Sum_{k=1..n} binomial(n,k)^2 * A002895(k) * k * a(n-k).
%t A336637 nmax = 15; CoefficientList[Series[Exp[BesselI[0, 2 Sqrt[x]]^4 - 1], {x, 0, nmax}], x] Range[0, nmax]!^2
%t A336637 a[0] = 1; a[n_] := a[n] = (1/n) Sum[Binomial[n, k]^2 Binomial[2 k, k] HypergeometricPFQ[{1/2, -k, -k, -k}, {1, 1, 1/2 - k}, 1] k a[n - k], {k, 1, n}]; Table[a[n], {n, 0, 15}]
%Y A336637 Cf. A002895, A023998, A336635, A336636.
%K A336637 nonn
%O A336637 0,2
%A A336637 _Ilya Gutkovskiy_, Jul 28 2020