A055899 Column 3 of triangle A055898.

1, 7, 31, 101, 272, 636, 1340, 2600, 4725, 8135, 13391, 21217, 32536, 48496, 70512, 100296, 139905, 191775, 258775, 344245, 452056, 586652, 753116, 957216, 1205477, 1505231, 1864695, 2293025, 2800400, 3398080, 4098496, 4915312

Offset

3,2

Links

Table of n, a(n) for n=3..34.

A. J. Guttmann, Indicators of solvability for lattice models, Discrete Math., 217 (2000), 167-189 (H_3 for square lattices of Section 6).

Formula

G.f.: x^3(1+2x+4x^2+2x^3+x^4)/((1-x)^7(1+x)^2). [Corrected by Georg Fischer, Aug 16 2021]

Mathematica

CoefficientList[Series[(1+2*x+4*x^2+2*x^3+x^4)/((1-x)^7*(1+x)^2), {x, 0, 40}], x] (* Georg Fischer, Aug 16 2021 *)

Crossrefs

Cf. A055898 (triangle), A055900 (column 4), A055901 (5), A055902 (6), A055903 (7), A055904 (8).

Sequence in context: A193437 A199921 A192596 * A218956 A139876 A222265

Adjacent sequences: A055896 A055897 A055898 * A055900 A055901 A055902

Keyword

nonn,easy

Author

Christian G. Bower, Jun 13 2000

Status

approved