A052755 G.f. A(x) satisfies: A(x) = exp( Sum_{k>=1} (-1)^(k+1) * A(x^k)^3 * x^k / k )

1, 1, 3, 15, 79, 466, 2872, 18409, 121197, 815491, 5581214, 38737651, 272012178, 1928939678, 13794498614, 99371002295, 720411445866, 5252194141946, 38482834469488, 283223825607253, 2092829973445703

Offset

0,3

Comments

Old name was: A simple grammar.

Links

Table of n, a(n) for n=0..20.

INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 711

Formula

G.f. A(x) satisfies: A(x) = exp( Sum_{k>=1} (-1)^(k+1) * A(x^k)^3 * x^k / k ). - Ilya Gutkovskiy, May 26 2023

Maple

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

Crossrefs

Cf. A005754, A052775, A052798.

Sequence in context: A186942 A193913 A292097 * A137957 A002514 A319216

Adjacent sequences: A052752 A052753 A052754 * A052756 A052757 A052758

Keyword

easy,nonn

Author

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

Extensions

New name from Ilya Gutkovskiy, May 26 2023

Status

approved