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A055915 Column 9 of triangle A055907. 2
1, 18, 164, 1050, 5367, 23232, 88125, 299992, 932849, 2685747, 7235237, 18392853, 44427807, 102552852, 227298680, 485679518, 1003915611, 2013360324, 3927664296, 7469755903, 13876848040, 25225619858, 44911485414 (list; graph; refs; listen; history; text; internal format)
OFFSET

9,2

LINKS

Table of n, a(n) for n=9..31.

A. J. Guttmann and A. R. Conway, Hexagonal lattice directed site animals, Statistical Physics on the Eve of the Twenty-First Century, ed. M. T. Batchelor, World Scientific, 1999 (H_9 for hexagonal lattices Table 1).

FORMULA

G.f.: x^9*B(x)/((1-x)^19*(1+x)^9*(1+x^2)^8*(1+x^2+x^4)^6*(1+x^4)^4*(1+x^2+x^4+x^6+x^8)^2) where B(x) is g.f. of A055918.

CROSSREFS

Sequence in context: A008418 A099196 A041618 * A208827 A071539 A125381

Adjacent sequences:  A055912 A055913 A055914 * A055916 A055917 A055918

KEYWORD

nonn

AUTHOR

Christian G. Bower, Jun 22 2000

STATUS

approved

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Last modified October 14 08:54 EDT 2019. Contains 327995 sequences. (Running on oeis4.)