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 A180589 #7 Apr 20 2025 12:33:50
%S A180589 1,1,3,12,54,294,1866,13698,114064,1062864,10958530,123870240,
%T A180589 1523289156,20247546240,289277533440,4420892649600,71965034739952,
%U A180589 1243166003251200,22713955095665178,437647401838080000,8868800513341440000,188567126333429760000,4197346376195350706086
%N A180589 a(n) = floor(n!*h(n)/n), where h(n) = Sum_{k=1..n} 1/k.
%F A180589 a(n) = (A000254(n) - A061006(n))/n.
%p A180589 h:= n->sum(1/k,k=1..n):seq(floor(n!*h(n)/n),n=1..25);
%t A180589 a[n_]:=Floor[n!*Sum[1/k,{k,n}]/n]; Array[a,23] (* _Stefano Spezia_, Apr 20 2025 *)
%Y A180589 Cf. A000254, A061006.
%K A180589 nonn
%O A180589 1,3
%A A180589 _Gary Detlefs_, Sep 10 2010
%E A180589 a(21)-a(23) from _Stefano Spezia_, Apr 20 2025