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 A308390 #8 May 24 2019 16:39:44
%S A308390 1,-1,56,-52556,197741887,-2063348839223,48406314676155689,
%T A308390 -2224972937386763396470,181775891472021264149048031,
%U A308390 -24546223741277444828277125708238,5178698199109137849496232609026642706,-1632057854975794517762778147823325297971400
%N A308390 a(n) = (1/n!) * Sum_{i_1=1..5} Sum_{i_2=1..5} ... Sum_{i_n=1..5} (-1)^(i_1 + i_2 + ... + i_n) * multinomial(i_1 + i_2 + ... + i_n; i_1, i_2, ..., i_n).
%o A308390 (PARI) {a(n) = sum(i=n, 5*n, (-1)^i*i!*polcoef(sum(j=1, 5, x^j/j!)^n, i))/n!}
%Y A308390 Row n=5 of A308356.
%Y A308390 Cf. A144509.
%K A308390 sign
%O A308390 0,3
%A A308390 _Seiichi Manyama_, May 23 2019