A052877 E.g.f.: exp(x)-1+log(-1/(-2+exp(x))).

0, 2, 3, 7, 27, 151, 1083, 9367, 94587, 1091671, 14174523, 204495127, 3245265147, 56183135191, 1053716696763, 21282685940887, 460566381955707, 10631309363962711, 260741534058271803, 6771069326513690647

Offset

0,2

Comments

Previous name was: A simple grammar.

Links

Table of n, a(n) for n=0..19.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 848

Formula

E.g.f.: exp(x)-1+log(-1/(-2+exp(x)))

a(n) ~ (n-1)! / log(2)^n. - Vaclav Kotesovec, Sep 30 2013

Maple

spec := [S, {B=Set(Z, 1 <= card), C=Cycle(B), S=Union(B, C)}, labeled]: seq(combstruct[count](spec, size=n), n=0..20);

Mathematica

CoefficientList[Series[E^x-1+Log[-1/(-2+E^x)], {x, 0, 20}], x]* Range[0, 20]! (* Vaclav Kotesovec, Sep 30 2013 *)

Crossrefs

a(n) = A000629(n-1)+1, n>0. Cf. A002050.

Sequence in context: A128001 A264829 A156142 * A137075 A270347 A060412

Adjacent sequences: A052874 A052875 A052876 * A052878 A052879 A052880

Keyword

easy,nonn

Author

encyclopedia(AT)pommard.inria.fr, Jan 25 2000

Extensions

New name, using e.g.f., from Vaclav Kotesovec, Sep 30 2013

Status

approved