A055912 Column 6 of triangle A055907.

1, 12, 74, 331, 1212, 3829, 10778, 27651, 65745, 146663, 309831, 624423, 1207701, 2252494, 4067393, 7134576, 12191298, 20342987, 33217622, 53174235, 83580380, 129177701, 196557754, 294776792, 436141322, 637204826, 920020667

Offset: 6

Author

Christian G. Bower, Jun 22 2000

Keywords

• nonn

Links

• A. J. Guttmann and A. R. Conway, Hexagonal lattice directed site animals, Statistical Physics on the Eve of the Twenty-First Century, ed. M. T. Batchelor, World Scientific, 1999 (H_6 for hexagonal lattices Table 1).

Crossrefs

Cf. A055907.

Formula

G.f.: x^6(1 + 5x + 13x^2 + 40x^3 + 85x^4 + 160x^5 + 297x^6 + 453x^7 + 711x^8 + 956x^9 + 1276x^10 + 1614x^11 + 1798x^12 + 2192x^13 + 2064x^14 + 2446x^15 + 1949x^16 + 2220x^17 + 1546x^18 + 1642x^19 + 1011x^20 + 959x^21 + 558x^22 + 427x^23 + 249x^24 + 135x^25 + 85x^26 + 32x^27 + 15x^28 + 8x^29 + x^31)/((1 - x)^13(1 + x)^6(1 + x^2)^5(1 + x^2 + x^4)^3(1 + x^4)). [See column t6,m in table 1 p. 12 of Guttmann and Conway.]