OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..500
FORMULA
G.f.: see Maple program.
EXAMPLE
a(2) = 13, because there are 13 tilings of a 6 X 2 rectangle using integer-sided square tiles:
._._. .___. ._._. ._._. ._._. ._._.
|_|_| | | |_|_| |_|_| |_|_| |_|_|
|_|_| |___| | | |_|_| |_|_| |_|_|
|_|_| |_|_| |___| | | |_|_| |_|_|
|_|_| |_|_| |_|_| |___| | | |_|_|
|_|_| |_|_| |_|_| |_|_| |___| | |
|_|_| |_|_| |_|_| |_|_| |_|_| |___|
.___. .___. .___. ._._. ._._. ._._. .___.
| | | | | | |_|_| |_|_| |_|_| | |
|___| |___| |___| | | | | |_|_| |___|
| | |_|_| |_|_| |___| |___| | | | |
|___| | | |_|_| | | |_|_| |___| |___|
|_|_| |___| | | |___| | | | | | |
|_|_| |_|_| |___| |_|_| |___| |___| |___|
MAPLE
gf:= -(2*x^9 +3*x^8 +2*x^7 -3*x^6 -7*x^5 -4*x^4 -3*x^3 +5*x^2 +2*x -1) / (2*x^15 +7*x^14 +12*x^13 +6*x^12 -18*x^11 -13*x^10 -8*x^9 -27*x^8 -32*x^7 +x^6 +40*x^5 +34*x^4 -3*x^3 -15*x^2 -3*x +1):
a:= n-> coeff (series (gf, x, n+1), x, n):
seq (a(n), n=0..40);
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Alois P. Heinz, Dec 01 2012
STATUS
approved