OFFSET
0,3
LINKS
Alois P. Heinz, Table of n, a(n) for n = 0..1000
Wikipedia, Pentomino
Index entries for linear recurrences with constant coefficients, signature (0,2,1,12,6,2).
FORMULA
G.f.: -1/(2*x^6+6*x^5+12*x^4+x^3+2*x^2-1).
EXAMPLE
a(4) = 16:
._______. ._______. ._______.
| ._____| | ._____| | ._| ._|
|_| |_. | |_| |_. | | | | | |
|_. ._| | |_. ._| | | | | | |
| |_|___| | |_| | | |_| |_| |
|_______| (2) |_____|_| (4) |___|___| (4)
._______. ._______.
| ._____| | ._____|
|_| ._. | |_|_. | |
| |_| |_| | ._| | |
|_____| | | |___| |
|_______| (2) |___|___| (4) .
MAPLE
a:= n-> (<<0|1|0|0|0|0>, <0|0|1|0|0|0>, <0|0|0|1|0|0>,
<0|0|0|0|1|0>, <0|0|0|0|0|1>, <2|6|12|1|2|0>>^n)[6, 6]:
seq(a(n), n=0..40);
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Nov 19 2014
STATUS
approved