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Column 3 of triangle A055907.
1

%I #6 Aug 17 2021 02:48:19

%S 1,6,20,53,121,249,471,836,1409,2276,3544,5350,7862,11286,15866,21896,

%T 29721,39746,52436,68331,88047,112287,141841,177604,220577,271880,

%U 332752,404572,488860,587292,701700,834096,986673,1161822,1362132

%N Column 3 of triangle A055907.

%H A. J. Guttmann, <a href="https://doi.org/10.1016/S0012-365X(99)00262-9">Indicators of solvability for lattice models</a>, Discrete Math., 217 (2000), 167-189 (H_3 for hexagonal lattices of Section 6).

%F G.f.: x^3*(1+x)*(1+x+3x^3-x^4+x^5) / ((1-x)^7*(1+x)^3*(1+x^2)^2).

%Y Cf. A055907.

%K nonn

%O 3,2

%A _Christian G. Bower_, Jun 14 2000