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 A336248 #8 Jul 14 2020 21:39:41
%S A336248 1,0,1,26,20481,774403124,2173797080953345,645067515585218711490294,
%T A336248 27280857986486289638369834192338945,
%U A336248 213095986405176211170558965907644717041658073416,386654453940903446694477049963665295677203885863801760000000001
%N A336248 a(n) = (n!)^n * Sum_{k=0..n} (-1)^k / (k!)^n.
%t A336248 Table[(n!)^n Sum[(-1)^k/(k!)^n, {k, 0, n}], {n, 0, 10}]
%o A336248 (PARI) a(n) = (n!)^n * sum(k=0, n, (-1)^k / (k!)^n); \\ _Michel Marcus_, Jul 14 2020
%Y A336248 Cf. A000166, A036740, A073701, A336247.
%K A336248 nonn
%O A336248 0,4
%A A336248 _Ilya Gutkovskiy_, Jul 14 2020