A109995 Number of unlabeled ordered minimal T_0-covers of an n-set, cf. A094545.

1, 1, 1, 2, 5, 18, 86, 549, 4647, 52060, 772976, 15240116, 400345371, 14063594530, 663256392496, 42161077371566, 3625838175218123, 423372648479289300, 67333725775723184308, 14628921614102655999804, 4352732830667872529962044

Offset: 0

Author

Goran Kilibarda, Vladeta Jovovic, Sep 01 2005

Keywords

• easy
• nonn

Links

• G. C. Greubel, Table of n, a(n) for n = 0..119

Programs

Mathematica

Table[Sum[Binomial[2^m-m-1, n-m], {m,0,n}], {n, 0, 50}] (* G. C. Greubel, Oct 08 2017 *)

PARI

for(n=0,50, print1(sum(m=0,n, binomial(2^m -m -1, n-m)), ", ")) \\ G. C. Greubel, Oct 08 2017

Formula

a(n) = Sum_{m=0..n} binomial(2^m-m-1, n-m).