A055908 Column 2 of triangle A055907.

1, 4, 10, 21, 39, 67, 107, 163, 238, 337, 463, 622, 818, 1058, 1346, 1690, 2095, 2570, 3120, 3755, 4481, 5309, 6245, 7301, 8484, 9807, 11277, 12908, 14708, 16692, 18868, 21252, 23853, 26688, 29766, 33105, 36715, 40615, 44815, 49335, 54186

Offset

2,2

Links

Table of n, a(n) for n=2..42.

A. J. Guttmann, Indicators of solvability for lattice models, Discrete Math., 217 (2000), 167-189 (H_2 for hexagonal lattices of Section 6).

Formula

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

Crossrefs

Cf. A055907.

Sequence in context: A253688 A049480 A216172 * A325951 A023538 A085360

Adjacent sequences: A055905 A055906 A055907 * A055909 A055910 A055911

Keyword

nonn

Author

Christian G. Bower, Jun 14 2000

Status

approved