A231690 Cardinalities of the sub-operad FF_6 of the operad MFF.

1, 6, 56, 640, 8158, 111258, 1588544, 23446248, 354855218, 5477342222, 85893429256, 1364577254040, 21916000458014, 355251287893170, 5804407209709312, 95493879511032240, 1580592247322440642, 26301843121772151254, 439764358275666481496, 7384252698468635017936, 124469446338979722639294

Offset: 1

Author

N. J. A. Sloane, Nov 14 2013

Keywords

• nonn

Links

• Gheorghe Coserea, Table of n, a(n) for n = 1..301
• F. Chapoton, F. Hivert, J.-C. Novelli, A set-operad of formal fractions and dendriform-like sub-operads, arXiv preprint arXiv:1307.0092 [math.CO], 2013.

Crossrefs

Cf. A213667, A231691.

Programs

Mathematica

InverseSeries[x(1 - 3x - x^2 + x^3)/(1 + 3x + x^2 - x^3) + O[x]^22] // CoefficientList[#, x]& // Rest (* Jean-François Alcover, Oct 24 2018, from PARI *)

PARI

N=22; x='x+O('x^N);
Vec(serreverse(Ser(x*(1-3*x-x^2+x^3)/(1+3*x+x^2-x^3))))  \\ Gheorghe Coserea, Jan 13 2017

Formula

A(x) = serreverse(A213667(-x))(-x). - Gheorghe Coserea, Jan 13 2017

Extensions

Offset changed and more terms from Gheorghe Coserea, Jan 13 2017