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

0,4

Links

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

Formula

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

Mathematica

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

Prog

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

Crossrefs

Sequence in context: A371800 A020029 A020119 * A142153 A287227 A094294

Adjacent sequences: A109992 A109993 A109994 * A109996 A109997 A109998

Keyword

easy,nonn

Author

Goran Kilibarda, Vladeta Jovovic, Sep 01 2005

Status

approved