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 A308323 #18 May 21 2019 11:34:51
%S A308323 1,0,3,-692,25413205,-247578134832564,1049539393188856278390451,
%T A308323 -2871690441592604257533055860715129272,
%U A308323 7040796701370550878156702345258827433898638874681737,-20490586759699718697495728993626502030472234718733294544426997558792280
%N A308323 a(n) = Sum_{i_1=0..n} Sum_{i_2=0..n} ... Sum_{i_n=0..n} (-1)^(i_1 + i_2 + ... + i_n) * multinomial(i_1 + i_2 + ... + i_n; i_1, i_2, ..., i_n).
%H A308323 Seiichi Manyama, <a href="/A308323/b308323.txt">Table of n, a(n) for n = 0..26</a>
%o A308323 (PARI) {a(n) = sum(i=0, n^2, (-1)^i*i!*polcoef(sum(j=0, n, x^j/j!)^n, i))}
%Y A308323 Main diagonal of A308322.
%Y A308323 Cf. A274762.
%K A308323 sign
%O A308323 0,3
%A A308323 _Seiichi Manyama_, May 20 2019