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 A355494 #16 Feb 18 2023 22:49:04
%S A355494 1,1,5,36,350,4328,65132,1155904,23640724,547544032,14166236708,
%T A355494 404944248104,12674392793900,431104742439088,15834117059443828,
%U A355494 624575921756875960,26332801242942780668,1181750740315156943936,56244454481507648435012
%N A355494 Expansion of Sum_{k>=0} (k * x/(1 - x))^k.
%H A355494 Winston de Greef, <a href="/A355494/b355494.txt">Table of n, a(n) for n = 0..385</a>
%F A355494 a(n) = Sum_{k=1..n} k^k * binomial(n-1,k-1) for n > 0.
%F A355494 a(n) ~ exp(exp(-1)) * n^n. - _Vaclav Kotesovec_, Jul 05 2022
%t A355494 Join[{1}, Table[Sum[k^k * Binomial[n-1,k-1], {k,1,n}], {n, 1, 20}]] (* _Vaclav Kotesovec_, Jul 05 2022 *)
%o A355494 (PARI) my(N=20, x='x+O('x^N)); Vec(sum(k=0, N, (k*x/(1-x))^k))
%o A355494 (PARI) a(n) = if(n==0, 1, sum(k=1, n, k^k*binomial(n-1, k-1)));
%Y A355494 Cf. A355495, A355496.
%Y A355494 Cf. A086331.
%K A355494 nonn
%O A355494 0,3
%A A355494 _Seiichi Manyama_, Jul 04 2022