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 A354897 #15 Jun 11 2022 07:52:19
%S A354897 1,5,28,353,3126,94237,823544,72042497,585825130,157671732881,
%T A354897 285311670612,790577855833537,302875106592254,5876819345289651137,
%U A354897 55890419425648520176,73205730667453550166017,827240261886336764178,1474631675630757976051079425
%N A354897 a(n) = n! * Sum_{d|n} d^n / (d! * (n/d)!).
%F A354897 E.g.f.: Sum_{k>0} (exp((k * x)^k) - 1)/k!.
%F A354897 If p is prime, a(p) = 1 + p^p.
%t A354897 a[n_] := n! * DivisorSum[n, #^n/(#! * (n/#)!) &]; Array[a, 18] (* _Amiram Eldar_, Jun 11 2022 *)
%o A354897 (PARI) a(n) = n!*sumdiv(n, d, d^n/(d!*(n/d)!));
%o A354897 (PARI) my(N=20, x='x+O('x^N)); Vec(serlaplace(sum(k=1, N, (exp((k*x)^k)-1)/k!)))
%Y A354897 Cf. A121860, A354844, A354890, A354892, A354893, A354898, A354899.
%K A354897 nonn
%O A354897 1,2
%A A354897 _Seiichi Manyama_, Jun 11 2022