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
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
KEYWORD
nonn,easy
AUTHOR
Jonathan Vos Post, Oct 26 2009
EXTENSIONS
Edited by Ralf Stephan, Feb 07 2014
STATUS
approved