OFFSET
0,2
COMMENTS
The count compiles all arrangements without respect to symmetry: Stacks that are equivalent after rotations or flips through any of the 3 axes or 3 planes are counted with multiplicity.
LINKS
Vincenzo Librandi, Table of n, a(n) for n = 0..200
R. J. Mathar, Tilings of rectangular regions by rectangular tiles: counts derived from transfer matrices, arXiv:1406.7788 [math.CO], eq. (44).
Index entries for linear recurrences with constant coefficients, signature (55,-700,3186,-5180,2640).
FORMULA
G.f.: (1-2*x)*(-120*x^3+122*x^2-24*x+1) / ( (1-x) *(2640*x^4-2540*x^3+646*x^2-54*x+1) ) .
MAPLE
MATHEMATICA
CoefficientList[Series[(1 - 2 x) (-120 x^3 + 122 x^2 - 24 x + 1)/((1 - x) (2640 x^4 - 2540 x^3 + 646 x^2 - 54 x + 1)), {x, 0, 30}], x] (* Vincenzo Librandi, Feb 08 2014 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
R. J. Mathar, Feb 07 2014
STATUS
approved