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 A346405 #5 Jul 15 2021 21:21:08
%S A346405 0,1,5,31,268,3476,70656,2202432,98622336,5954736384,463100042880,
%T A346405 44924476970880,5308404719823360,749930460864929280,
%U A346405 124754522068412651520,24129984694192721971200,5368254991077002482483200,1360938718277588430567014400,389980903967231535140578099200
%N A346405 a(n) = (n!)^2 * Sum_{k=0..n-1} 1 / ((n-k)^2 * k!).
%F A346405 Sum_{n>=0} a(n) * x^n / (n!)^2 = polylog(2,x) * exp(x).
%t A346405 Table[(n!)^2 Sum[1/((n - k)^2 k!), {k, 0, n - 1}], {n, 0, 18}]
%t A346405 nmax = 18; CoefficientList[Series[PolyLog[2, x] Exp[x], {x, 0, nmax}], x] Range[0, nmax]!^2
%Y A346405 Cf. A001819, A002104, A002720, A061573, A346409.
%K A346405 nonn
%O A346405 0,3
%A A346405 _Ilya Gutkovskiy_, Jul 15 2021