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

1, 1, 2, 3, 3, 60, 360, 70, 1680, 3780, 75600, 138600, 285120, 129729600, 363242880, 3405402000, 1009008000, 308756448000, 5557616064000, 52797352608000, 351982350720000, 221748880953600, 1524523556556000, 738190353700800, 13464592051502592000

Offset: 0

Author

Alois P. Heinz, Jan 11 2019

Keywords

• nonn
• frac

Comments

Denominators of the INVERT transform of reciprocal integers.

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..506

Crossrefs

See A323339 for more information.

Cf. A000142, A007840.

Programs

Maple

b:= proc(n) option remember;
     `if`(n=0, 1, add(b(n-j)/j, j=1..n))
    end:
a:= n-> denom(b(n)):
seq(a(n), n=0..25);

Mathematica

nmax = 20; Denominator[CoefficientList[Series[1/(1 + Log[1-x]), {x, 0, nmax}], x]] (* Vaclav Kotesovec, Feb 12 2024 *)

Formula

a(n) = denominator( A007840(n)/n! ).