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A055907

Triangle: number of directed site animals on hexagonal net (honeycomb) with n total sites and k sites supported in one particular way.

0, 1, 1, 1, 2, 1, 1, 4, 4, 1, 1, 6, 10, 6, 1, 1, 9, 21, 20, 8, 1, 1, 12, 39, 53, 36, 10, 1, 1, 16, 67, 121, 128, 56, 12, 1, 1, 20, 107, 249, 388, 240, 74, 14, 1, 1, 25, 163, 471, 1050, 854, 331, 100, 16, 1, 1, 30, 238, 836, 2601, 2654, 1212, 511, 130, 18, 1, 1, 36, 337

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OFFSET

0,5

LINKS

Table of n, a(n) for n=0..68.

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

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 (F_h of Section 4).

EXAMPLE

Table begins:

1, 1;

1, 2, 1;

1, 4, 4, 1;

1, 6, 10, 6, 1;

...

CROSSREFS

Row sums give A055919.

Columns 1-9 give: A002620(n+1), A055908, A055909, A055910, A055911, A055912, A055913, A055914, A055915.

Cf. A055898.

Sequence in context: A157528 A132731 A128966 * A259698 A274643 A172991