A052890 A simple grammar.

1, 1, 2, 6, 16, 49, 153, 493, 1623, 5460, 18625, 64373, 224843, 792546, 2815443, 10070115, 36233440, 131063713, 476320360, 1738401482, 6368750019, 23413000913, 86342448134, 319329672079, 1184129737292, 4401635480735, 16398478453303, 61220441044887

Offset

0,3

Links

Table of n, a(n) for n=0..27.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 866

Maple

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

Crossrefs

Sequence in context: A151528 A132803 A079565 * A052814 A192401 A151445

Adjacent sequences: A052887 A052888 A052889 * A052891 A052892 A052893

Keyword

easy,nonn

Author

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

Extensions

More terms from Sean A. Irvine, Dec 01 2021

Status

approved