A226371 Number of tilings of a 7 X n rectangle using integer-sided square tiles of area > 1.

1, 0, 0, 0, 0, 0, 7, 1, 0, 0, 2, 0, 57, 16, 1, 0, 32, 4, 463, 197, 29, 1, 392, 100, 3767, 2150, 518, 46, 4267, 1668, 30763, 21953, 7454, 1128, 43531, 23057, 252755, 215070, 94769, 20728, 426847, 285548, 2094102, 2050219, 1112227, 321677, 4080855, 3290655

Offset: 0

Author

Alois P. Heinz, Jun 05 2013

Keywords

• nonn
• easy

Examples

			a(10) = 2:
._._._._._._._._._._.   ._._._._._._._._._._.
|         |         |   |   |   |   |   |   |
|         |         |   |___|___|___|___|___|
|         |         |   |         |         |
|         |         |   |         |         |
|_________|_________|   |         |         |
|   |   |   |   |   |   |         |         |
|___|___|___|___|___|   |_________|_________|
		

Links

• Alois P. Heinz, Table of n, a(n) for n = 0..1000

Crossrefs

Column k=7 of A226206.

Programs

Maple

a:= n-> coeff(series((-x^12-x^9+2*x^6+x^3-1) / (x^19 -x^18 -x^16 -x^15 -2*x^13 -7*x^12 +x^10 -8*x^9 +x^7 +9*x^6 +x^3-1), x, n+1), x, n):
seq(a(n), n=0..70);

Formula

G.f.: (-x^12-x^9+2*x^6+x^3-1) / (x^19 -x^18 -x^16 -x^15 -2*x^13 -7*x^12 +x^10 -8*x^9 +x^7 +9*x^6 +x^3-1).