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 A355375 #15 Jun 30 2022 10:27:29
%S A355375 1,1,0,-4,10,67,-969,3341,86976,-1988704,14144108,405611857,
%T A355375 -17544321563,287677263837,3595470378748,-421298868094940,
%U A355375 14476946230894114,-112253861285434961,-18711849695261432065,1354595712379990848137,-44436925726445545236496
%N A355375 a(n) = Sum_{k=0..n} (-k)^(n-k) * Stirling2(n,k).
%F A355375 E.g.f.: Sum_{k>=0} (1 - exp(-k * x))^k / (k^k * k!).
%t A355375 a[n_] := Sum[(-k)^(n - k) * StirlingS2[n, k], {k, 0, n}]; a[0] = 1; Array[a, 20, 0] (* _Amiram Eldar_, Jun 30 2022 *)
%o A355375 (PARI) a(n) = sum(k=0, n, (-k)^(n-k)*stirling(n, k, 2));
%o A355375 (PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(sum(k=0, N, (1-exp(-k*x))^k/(k^k*k!))))
%Y A355375 Cf. A229233, A232549, A318183, A355376.
%K A355375 sign
%O A355375 0,4
%A A355375 _Seiichi Manyama_, Jun 30 2022