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

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_3 for hexagonal lattices of Section 6).

Crossrefs

Cf. A055907.

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).