A052891 Number of objects generated by the Combstruct grammar defined in the Maple program. See the link for the grammar specification.

0, 1, 2, 5, 16, 56, 217, 876, 3686, 15903, 70103, 314042, 1426076, 6548060, 30352695, 141837086, 667469159, 3160370217, 15045244375, 71970393570, 345766441537, 1667629158127, 8071308125136, 39190243658297, 190845259909328, 931856232714004, 4561292365652751

Offset

0,3

Links

Andrew Howroyd, Table of n, a(n) for n = 0..200

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 867

Maplesoft, Combstruct grammars.

Formula

G.f.: 1 - 1/g(x) where g(x) is the g.f. of A052893. - Andrew Howroyd, Aug 09 2020

Maple

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

Prog

(PARI) EulerT(v)={Vec(exp(x*Ser(dirmul(v, vector(#v, n, 1/n))))-1, -#v)}
seq(n)={my(v=[0]); for(n=1, n, v=concat([0], EulerT(Vec(1/(1-Ser(v)))))); v} \\ Andrew Howroyd, Aug 09 2020

Crossrefs

Cf. A052893.

Sequence in context: A141201 A149977 A147771 * A352905 A052815 A195931

Adjacent sequences: A052888 A052889 A052890 * A052892 A052893 A052894

Keyword

easy,nonn

Author

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

Extensions

Terms a(21) and beyond from Andrew Howroyd, Aug 09 2020

Status

approved