A242637 Number of quadrangulations of a hexagon having n inner faces.

0, 0, 3, 14, 63, 294, 1428, 7182, 37191, 197340, 1068795, 5890248, 32950148, 186722424, 1070140344, 6194466222, 36174046743, 212916311160, 1262089449705, 7529078811870, 45175862512935, 272496191425710, 1651614288826320, 10054944326873160, 61464207807747108

Offset

0,3

Links

Andrew Howroyd, Table of n, a(n) for n = 0..500

Sergey Kitaev, Anna de Mier, Marc Noy, On the number of self-dual rooted maps, European J. Combin. 35, 2014, pp377-387, MR3090510.

Formula

G.f.: (3 - 7*g(x))*g(x)^2/(1 - g(x))^3 where g(x)/x is the g.f. of A006013. - Andrew Howroyd, Feb 23 2020

Prog

(PARI) seq(n)={my(g=serreverse(x*(1-x)^2 + O(x^n))); Vec((3 - 7*g)*g^2/(1 - g)^3, -(n+1))} \\ Andrew Howroyd, Feb 23 2020

Crossrefs

Cf. A006013, A242638.

Sequence in context: A291025 A320499 A091701 * A151237 A151238 A026243

Adjacent sequences: A242634 A242635 A242636 * A242638 A242639 A242640

Keyword

nonn

Author

N. J. A. Sloane, May 19 2014

Extensions

Terms a(6) and beyond from Andrew Howroyd, Feb 23 2020

Status

approved