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

Author

Christian G. Bower, Jun 14 2000

Keywords

• nonn

Links

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

Crossrefs

Cf. A055907.

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)).