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 A355987 #22 Sep 24 2023 09:30:34
%S A355987 1,3,13,61,421,2641,23521,203281,2071441,22407841,286403041,
%T A355987 3453468481,51122111041,759194916481,12216117513601,203300293996801,
%U A355987 3811792426041601,69634723878720001,1444704854104512001,29725332567567436801,658231789483184716801
%N A355987 a(n) = n! * Sum_{k=1..n} 1/floor(n/k)!.
%F A355987 E.g.f.: (1/(1-x)) * Sum_{k>0} (1 - x^k) * (exp(x^k) - 1).
%F A355987 a(n) ~ c * n! * n, where c = 0.59962032... - _Vaclav Kotesovec_, Aug 03 2022
%F A355987 Conjecture: c = Sum_{k>=1} 1/((k+1)!*k) = 2 - exp(1) - A001620 + A091725. - _Vaclav Kotesovec_, Sep 24 2023
%t A355987 a[n_] := n! * Sum[1/Floor[n/k]!, {k, 1, n}]; Array[a, 21] (* _Amiram Eldar_, Jul 22 2022 *)
%o A355987 (PARI) a(n) = n!*sum(k=1, n, 1/(n\k)!);
%o A355987 (PARI) my(N=30, x='x+O('x^N)); Vec(serlaplace(sum(k=1,N, (1-x^k)*(exp(x^k)-1))/(1-x)))
%Y A355987 Cf. A007489, A081125, A345683, A355886, A355988, A355991.
%K A355987 nonn
%O A355987 1,2
%A A355987 _Seiichi Manyama_, Jul 22 2022