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 A121564 #12 Oct 19 2024 20:07:44
%S A121564 1,1,2,18,288,180000,1620000,190591380000,780662292480000,
%T A121564 46097327708651520000,28810829817907200000000,
%U A121564 747278726094210559615027200000000,747278726094210559615027200000000,17410163370762081276553474535120146483200000000
%N A121564 Denominator of Sum_{i=1..n} i!/(i^i).
%F A121564 Denominator of Sum_{i=1..n} A000142(i)/A000312(i).
%F A121564 Limit_{n -> oo} A121563(n)/A121564(n) = A094082.
%e A121564 A121563/A121564 = 0, 1, 3/2, 31/18, 523/288, 333787/180000, ... .
%t A121564 Denominator[Table[Sum[i!/(i^i),{i,n}],{n,12}]] (* _James C. McMahon_, Oct 19 2024 *)
%Y A121564 Numerators are in A121563.
%Y A121564 Cf. A000142, A000312, A055775, A094082.
%K A121564 easy,frac,nonn
%O A121564 0,3
%A A121564 _Jonathan Vos Post_, Aug 07 2006