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 A352470 #5 Mar 18 2022 00:13:18
%S A352470 1,1,4,37,608,15601,576472,28993693,1904637184,158352856129,
%T A352470 16253786050904,2018684970206653,298373110433984192,
%U A352470 51757706826973479697,10412613242348421164400,2404755328388872932588037,631887117002962512609921024,187441600433239155105076467457
%N A352470 a(0) = 1; a(n) = Sum_{k=0..floor((n-1)/2)} binomial(n,2*k+1)^2 * a(n-2*k-1).
%F A352470 Sum_{n>=0} a(n) * x^n / n!^2 = 1 / (1 - Sum_{n>=0} x^(2*n+1) / (2*n+1)!^2).
%F A352470 Sum_{n>=0} a(n) * x^n / n!^2 = 1 / (1 - (BesselI(0,2*sqrt(x)) - BesselJ(0,2*sqrt(x))) / 2).
%t A352470 a[0] = 1; a[n_] := a[n] = Sum[Binomial[n, 2 k + 1]^2 a[n - 2 k - 1], {k, 0, Floor[(n - 1)/2]}]; Table[a[n], {n, 0, 17}]
%t A352470 nmax = 17; CoefficientList[Series[1/(1 - Sum[x^(2 k + 1)/(2 k + 1)!^2, {k, 0, nmax}]), {x, 0, nmax}], x] Range[0, nmax]!^2
%Y A352470 Cf. A006154, A102221, A346220, A352467, A352471.
%K A352470 nonn
%O A352470 0,3
%A A352470 _Ilya Gutkovskiy_, Mar 17 2022