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 A337826 #4 Sep 24 2020 14:00:08 %S A337826 1,1,10,105,2248,62445,2390436,116650177,7043659904,514744959321, %T A337826 44534754680500,4493090921151261,521600149636044480, %U A337826 68900819660071184149,10259571068808850618480,1708054303772376318547125,315688007001129064574027776,64370788231256983836207599153 %N A337826 a(0) = 1; a(n) = (1/n) * Sum_{k=1..n} binomial(n,k)^2 * k^4 * a(n-k). %F A337826 Sum_{n>=0} a(n) * x^n / (n!)^2 = exp(x * (BesselI(0,2*sqrt(x)) + sqrt(x) * BesselI(1,2*sqrt(x)))). %F A337826 Sum_{n>=0} a(n) * x^n / (n!)^2 = exp(Sum_{n>=1} n^3 * x^n / (n!)^2). %t A337826 a[0] = 1; a[n_] := a[n] = (1/n) Sum[Binomial[n, k]^2 k^4 a[n - k], {k, 1, n}]; Table[a[n], {n, 0, 17}] %t A337826 nmax = 17; CoefficientList[Series[Exp[x (BesselI[0, 2 Sqrt[x]] + Sqrt[x] BesselI[1, 2 Sqrt[x]])], {x, 0, nmax}], x] Range[0, nmax]!^2 %Y A337826 Cf. A023998, A279358, A336227, A337591, A337825. %K A337826 nonn %O A337826 0,3 %A A337826 _Ilya Gutkovskiy_, Sep 24 2020