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A055909 Column 3 of triangle A055907. 0
1, 6, 20, 53, 121, 249, 471, 836, 1409, 2276, 3544, 5350, 7862, 11286, 15866, 21896, 29721, 39746, 52436, 68331, 88047, 112287, 141841, 177604, 220577, 271880, 332752, 404572, 488860, 587292, 701700, 834096, 986673, 1161822, 1362132 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,2

LINKS

Table of n, a(n) for n=3..37.

A. J. Guttmann, Indicators of solvability for lattice models, Discrete Math., 217 (2000), 167-189 (H_3 for hexagonal lattices of Section 6).

FORMULA

G.f.: x^3(1+x)(1+x+3x^3-x^4+x^5) / ((1-x)^7(1+x)^3(1+x^2)^2).

CROSSREFS

Sequence in context: A275112 A027178 A264314 * A036596 A298408 A038091

Adjacent sequences:  A055906 A055907 A055908 * A055910 A055911 A055912

KEYWORD

nonn

AUTHOR

Christian G. Bower, Jun 14 2000

STATUS

approved

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Last modified October 16 16:18 EDT 2019. Contains 328101 sequences. (Running on oeis4.)