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 A293848 #20 Jun 14 2025 11:27:50
%S A293848 1,1,9,187,7033,421341,37025881,4500154639,723834652017,
%T A293848 148905928574713,38133707320119241,11894979981772431171,
%U A293848 4439223538343665367209,1952818695816854110909717,999887879061130705615605273,589500991222520435444933020951
%N A293848 E.g.f.: exp(Sum_{n>=1} n^n*x^n).
%H A293848 Seiichi Manyama, <a href="/A293848/b293848.txt">Table of n, a(n) for n = 0..232</a>
%F A293848 a(0) = 1 and a(n) = (n-1)! * Sum_{k=1..n} k^(k+1)*a(n-k)/(n-k)! for n > 0.
%F A293848 a(n) ~ n! * n^n. - _Vaclav Kotesovec_, Oct 18 2017
%t A293848 nmax = 20; CoefficientList[Series[E^Sum[k^k*x^k, {k, 1, nmax}], {x, 0, nmax}], x] * Range[0, nmax]! (* _Vaclav Kotesovec_, Oct 18 2017 *)
%o A293848 (PARI) {a(n) = n!*polcoeff(exp(sum(k=1, n, k^k*x^k)+x*O(x^n)), n)}
%Y A293848 Cf. A000312, A293847, A293849.
%K A293848 nonn
%O A293848 0,3
%A A293848 _Seiichi Manyama_, Oct 17 2017