cp's OEIS Frontend

A323340 Denominator of the sum of inverse products of parts in all compositions of n.

%I A323340 #12 Feb 12 2024 07:57:59
%S A323340 1,1,2,3,3,60,360,70,1680,3780,75600,138600,285120,129729600,
%T A323340 363242880,3405402000,1009008000,308756448000,5557616064000,
%U A323340 52797352608000,351982350720000,221748880953600,1524523556556000,738190353700800,13464592051502592000
%N A323340 Denominator of the sum of inverse products of parts in all compositions of n.
%C A323340 Denominators of the INVERT transform of reciprocal integers.
%H A323340 Alois P. Heinz, <a href="/A323340/b323340.txt">Table of n, a(n) for n = 0..506</a>
%F A323340 a(n) = denominator( A007840(n)/n! ).
%p A323340 b:= proc(n) option remember;
%p A323340      `if`(n=0, 1, add(b(n-j)/j, j=1..n))
%p A323340     end:
%p A323340 a:= n-> denom(b(n)):
%p A323340 seq(a(n), n=0..25);
%t A323340 nmax = 20; Denominator[CoefficientList[Series[1/(1 + Log[1-x]), {x, 0, nmax}], x]] (* _Vaclav Kotesovec_, Feb 12 2024 *)
%Y A323340 See A323339 for more information.
%Y A323340 Cf. A000142, A007840.
%K A323340 nonn,frac
%O A323340 0,3
%A A323340 _Alois P. Heinz_, Jan 11 2019