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 A336172 #19 Jul 11 2020 02:33:52 %S A336172 1,0,1,1109,58370761,616967236620839,2667424979594724623421841, %T A336172 7363013376580445620328429354795257679, %U A336172 18165626590057176919253932602358956717053291818375681,53130672834302729155813211757017136527240145191602729876485547920535679 %N A336172 a(n) = Sum_{k=0..n} (-1)^(n-k) * multinomial(n+(n-1)*k; n-k, {k}^n). %H A336172 Seiichi Manyama, <a href="/A336172/b336172.txt">Table of n, a(n) for n = 0..26</a> %F A336172 a(n) = [x^n] Sum_{k=0..n} (n*k)!/k!^n * x^k / (1+x)^(n*k+1). %t A336172 a[n_] := Sum[(-1)^(n - k)*(n + (n - 1)*k)!/((n - k)!*k!^n), {k, 0, n}]; Array[a, 10, 0] (* _Amiram Eldar_, Jul 10 2020 *) %o A336172 (PARI) {a(n) = sum(k=0, n, (-1)^(n-k)*(n+(n-1)*k)!/((n-k)!*k!^n))} %Y A336172 Main diagonal of A336169. %Y A336172 Cf. A229267. %K A336172 nonn %O A336172 0,4 %A A336172 _Seiichi Manyama_, Jul 10 2020