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

1,2

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.

Formula

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

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 *)

Prog

(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

Crossrefs

Cf. A213667, A231691.

Sequence in context: A025749 A365766 A297705 * A285166 A182955 A053336

Adjacent sequences: A231687 A231688 A231689 * A231691 A231692 A231693

Keyword

nonn

Author

N. J. A. Sloane, Nov 14 2013

Extensions

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

Status

approved