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 A346409 #5 Jul 15 2021 21:21:14
%S A346409 0,1,-3,13,-52,476,1344,156192,6935424,470168064,38948065920,
%T A346409 3979380286080,489922581219840,71586095491054080,12249193741572372480,
%U A346409 2426646293132502067200,551096248249459158220800,142236660450422499604070400,41404182857569072540171468800
%N A346409 a(n) = (n!)^2 * Sum_{k=0..n-1} (-1)^k / ((n-k)^2 * k!).
%F A346409 Sum_{n>=0} a(n) * x^n / (n!)^2 = polylog(2,x) * exp(-x).
%t A346409 Table[(n!)^2 Sum[(-1)^k/((n - k)^2 k!), {k, 0, n - 1}], {n, 0, 18}]
%t A346409 nmax = 18; CoefficientList[Series[PolyLog[2, x] Exp[-x], {x, 0, nmax}], x] Range[0, nmax]!^2
%Y A346409 Cf. A002741, A009940, A082491, A142999, A346405.
%K A346409 sign
%O A346409 0,3
%A A346409 _Ilya Gutkovskiy_, Jul 15 2021