A055910 Column 4 of triangle A055907.

1, 8, 36, 128, 388, 1050, 2601, 6013, 13141, 27416, 55012, 106816, 201685, 371828, 671630, 1192093, 2084360, 3597991, 6143128, 10391369, 17439285, 29073358, 48199071, 79535657, 130740732, 214230558, 350125952, 571019573, 929690344

Offset

4,2

Links

Table of n, a(n) for n=4..32.

A. J. Guttmann, Indicators of solvability for lattice models, Discrete Math., 217 (2000), 167-189 (H_4 for hexagonal lattices of Section 6).

Formula

G.f.: x^4*(1+3x+4x^2+10x^3+12x^4+14x^5+16x^6+13x^7+14x^8+7x^9+6x^10+4x^11+x^13)/ ((1-x)^9*(1+x)^4*(1+x^2)^3*(1-x-x^2)*(1+x+x^2)).

Crossrefs

Cf. A055907.

Sequence in context: A276279 A210379 A131123 * A022573 A014477 A034998

Adjacent sequences: A055907 A055908 A055909 * A055911 A055912 A055913

Keyword

nonn

Author

Christian G. Bower, Jun 14 2000

Status

approved