A052775 G.f. A(x) satisfies: A(x) = exp( Sum_{k>=1} (-1)^(k+1) * A(x^k)^4 * x^k / k ).

1, 1, 4, 26, 184, 1443, 11888, 101859, 897529, 8085103, 74113656, 689134849, 6484074328, 61620879930, 590628242876, 5703027934533, 55423681958153, 541689157201498, 5320989368024126, 52503593913927276

Offset: 0

Author

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

Keywords

• easy
• nonn

Comments

Old name was: A simple grammar.

Links

• INRIA Algorithms Project, Encyclopedia of Combinatorial Structures 732

Crossrefs

Cf. A005754, A052755, A052798.

Programs

Maple

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

Formula

G.f. A(x) satisfies: A(x) = exp( Sum_{k>=1} (-1)^(k+1) * A(x^k)^4 * x^k / k ). - Ilya Gutkovskiy, May 26 2023

Extensions

New name from Ilya Gutkovskiy, May 26 2023