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A090374 Number of rooted planar 4-constellations with n quadrangles: rooted planar maps with bicolored faces having n black quadrangular faces and an arbitrary number of white faces of degrees multiple to 4. 1
1, 10, 160, 3200, 72960, 1813504, 47923200, 1325629440, 37991219200, 1120005652480, 33789432561664, 1039157228994560, 32480974549811200, 1029463445864448000, 33023079530417356800, 1070513886720329515008, 35026358912891580579840, 1155516042520241436098560 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..18.

M. Bousquet-Mélou and G. Schaeffer, Enumeration of planar constellations, Adv. in Appl. Math. v.24 (2000), 337-368.

FORMULA

a(n) = 5*4^(n-1)*binomial(4*n, n)/((3*n+1)*(3*n+2)). - corrected by Michel Marcus, Dec 11 2014

MATHEMATICA

a[n_] := 5 2^(2n) (4n-1)! / ((n-1)! (3n+2)!);

Array[a, 18] (* Jean-François Alcover, Aug 28 2019 *)

PROG

(PARI) vector(20, n, 5*4^(n-1)*binomial(4*n, n)/((3*n+1)*(3*n+2))) \\ Michel Marcus, Dec 11 2014

CROSSREFS

Cf. A069729, A090373.

Sequence in context: A180881 A106261 A112125 * A034724 A234283 A074703

Adjacent sequences:  A090371 A090372 A090373 * A090375 A090376 A090377

KEYWORD

easy,nonn

AUTHOR

Valery A. Liskovets, Dec 01 2003

EXTENSIONS

More terms from Michel Marcus, Dec 11 2014

STATUS

approved

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Last modified December 13 22:53 EST 2019. Contains 329974 sequences. (Running on oeis4.)