OFFSET
0,2
LINKS
Michael De Vlieger, Table of n, a(n) for n = 0..3296
Robert Davis, Greg Simay, Further Combinatorics and Applications of Two-Toned Tilings, arXiv:2001.11089 [math.CO], 2020.
Index entries for linear recurrences with constant coefficients, signature (9, -33, 63, -66, 36, -8).
FORMULA
G.f.: 1/(((1-2*x)^3)*(1-x)^3).
a(n)= (n^2 - 3*n + 8)*(2^(n+3) -1)/2 - 9*(n+3). [Yahia Kahloune, Aug 11 2013]
MATHEMATICA
CoefficientList[Series[1/(((1 - 2 x)^3) (1 - x)^3), {x, 0, 25}], x] (* Michael De Vlieger, Apr 23 2020 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Wolfdieter Lang, May 26 2000
STATUS
approved