A167011 - OEIS

A167011

Number of Level 1 hexagonal polyominoes with cheesy blocks and n cells.

1, 3, 11, 44, 184, 784, 3363, 14451, 62097, 266716, 1145074, 4914448, 21087401, 90472315, 388129627, 1665025084, 7142592112, 30639836360, 131436162099, 563822359859, 2418629133001, 10375190596724, 44506436288882, 190919170388912, 818985577308225, 3513200788519075

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OFFSET

1,2

COMMENTS

From Table 1, p.24, of Feretic. By level 0 cheesy polyominoes, and so too by level 0 polyominoes with cheesy blocks, Feretic appears to mean the usual column-convex polyominoes (A059716). See the paper for his definition.

LINKS

Table of n, a(n) for n=1..26.

Svjetlan Feretic, Polyominoes with nearly convex columns: A model with semidirected blocks, Math. Commun. 15 (2010), 77--97, arXiv:0910.4780v1 [math.CO].

Wikipedia, Polyhex

Index entries for linear recurrences with constant coefficients, signature (9,-27,32,-13,3,1).

FORMULA

G.f.: x(-1+6x-11x^2+6x^3-2x^4)/(-1+9x-27x^2+32x^3-13x^4+3x^5+x^6).

MATHEMATICA

LinearRecurrence[{9, -27, 32, -13, 3, 1}, {1, 3, 11, 44, 184, 784}, 26] (* Ray Chandler, Jul 16 2015 *)

Rest[CoefficientList[Series[x*(-1+6x-11x^2+6x^3-2x^4)/(-1+9x-27x^2+32x^3-13x^4+3x^5+x^6), {x, 0, 26}], x]] (* Ray Chandler, Jul 16 2015 *)

CROSSREFS

Cf. A059716, A167012, A167013.