A055909 Column 3 of triangle A055907.

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

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

Cf. A055907.

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