OFFSET
0,12
LINKS
Alois P. Heinz, Antidiagonals n = 0..25, flattened
Wikipedia, Tromino
EXAMPLE
A(2,3) = A(3,2) = 14:
._____. ._____. ._____. ._____. ._____. ._____. ._____.
|_____| |_|_|_| |_____| |_| |_| | |_|_| | ._|_| |_. |_|
|_____| |_____| |_|_|_| |___|_| |___|_| |_|_|_| |_|_|_|
.
._____. ._____. ._____. ._____. ._____. ._____. ._____.
|_|_|_| | ._| | | |_. | |_|_| | |_| |_| |_| ._| |_|_. |
|_|_|_| |_|___| |___|_| |_|___| |_|___| |_|_|_| |_|_|_| .
.
Square array A(n,k) begins:
1, 1, 1, 1, 1, 1, 1, ...
1, 1, 1, 2, 3, 4, 6, ...
1, 1, 5, 14, 45, 140, 438, ...
1, 2, 14, 93, 590, 3710, 23509, ...
1, 3, 45, 590, 7517, 96176, 1238818, ...
1, 4, 140, 3710, 96176, 2501946, 65410388, ...
1, 6, 438, 23509, 1238818, 65410388, 3473827027, ...
CROSSREFS
KEYWORD
nonn,tabl
AUTHOR
Alois P. Heinz, Mar 09 2016
STATUS
approved