A052831 A simple grammar.

0, 1, 2, 4, 11, 29, 91, 286, 955, 3235, 11240, 39559, 141217, 509059, 1852248, 6790372, 25062536, 93043286, 347223013, 1301777476, 4900835727, 18519492431, 70220471264, 267080436295, 1018708832722, 3895714521787, 14933608764343, 57372586025039, 220869710184189

Offset

0,3

Links

Table of n, a(n) for n=0..28.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 796

Formula

G.f. satisfies A(x) = Sum_{j>=1} (phi(j)/j) * log( 1/(1-B(x^j)) ), where B(x) = x * exp( Sum_{j>=1} (-1)^(j+1) * S(x^j) / j ). - Sean A. Irvine, Dec 02 2021

Maple

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

Crossrefs

Sequence in context: A148145 A052869 A316768 * A339834 A148146 A148147

Adjacent sequences: A052828 A052829 A052830 * A052832 A052833 A052834

Keyword

easy,nonn

Author

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

Extensions

More terms from Sean A. Irvine, Dec 02 2021

Status

approved