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 A307324 #21 May 21 2019 03:49:41
%S A307324 1,9,997,148041,25413205,4744544613,935728207597,191813392024137,
%T A307324 40462946725744501,8726529512888314245,1915408781755211655133,
%U A307324 426478330303800465141669,96092667172064808771832957,21869171662479233922632691261
%N A307324 a(n) = Sum_{i=0..n} Sum_{j=0..n} Sum_{k=0..n} Sum_{l=0..n} (-1)^(i+j+k+l) * (i+j+k+l)!/(i!*j!*k!*l!).
%H A307324 Vaclav Kotesovec, <a href="/A307324/b307324.txt">Table of n, a(n) for n = 0..400</a>
%H A307324 Vaclav Kotesovec, <a href="/A307324/a307324.txt">Recurrence (of order 5)</a>
%F A307324 a(n) ~ 2^(8*n + 15/2) / (625 * Pi^(3/2) * n^(3/2)). - _Vaclav Kotesovec_, Apr 03 2019
%t A307324 Table[Sum[(-1)^(i + j + k + l) * (i + j + k + l)! / (i!*j!*k!*l!), {i, 0, n}, {j, 0, n}, {k, 0, n}, {l, 0, n}], {n, 0, 20}] (* _Vaclav Kotesovec_, Apr 02 2019 *)
%t A307324 Table[Sum[((-1)^(j + k + l) * 2^(-1 - j - k - l) * ((j + k + l)! * (1 + n)! + (-1)^n * 2^(1 + j + k + l) * (1 + j + k + l + n)! Hypergeometric2F1[1, 2 + j + k + l + n, 2 + n, -1]))/(j! k! l! (1 + n)!), {j, 0, n}, {k, 0, n}, {l, 0, n}], {n, 0, 20}] (* _Vaclav Kotesovec_, Apr 03 2019 *)
%o A307324 (PARI) {a(n) = sum(i=0, n, sum(j=0, n, sum(k=0, n, sum(l=0, n, (-1)^(i+j+k+l)*(i+j+k+l)!/(i!*j!*k!*l!)))))}
%o A307324 (PARI) {a(n) = sum(i=0, 4*n, (-1)^i*i!*polcoef(sum(j=0, n, x^j/j!)^4, i))} \\ _Seiichi Manyama_, May 20 2019
%Y A307324 Cf. A120305, A144661, A307318.
%K A307324 nonn
%O A307324 0,2
%A A307324 _Seiichi Manyama_, Apr 02 2019