A278657 - OEIS

A278657

Number A(n,k) of tilings of a k X n rectangle using pentominoes of any shape and monominoes; square array A(n,k), n>=0, k>=0, read by antidiagonals.

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 7, 7, 1, 1, 1, 2, 25, 50, 25, 2, 1, 1, 3, 50, 311, 311, 50, 3, 1, 1, 4, 155, 1954, 4101, 1954, 155, 4, 1, 1, 5, 508, 11914, 56864, 56864, 11914, 508, 5, 1, 1, 6, 1343, 76003, 728857, 1532496, 728857, 76003, 1343, 6, 1

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OFFSET

0,18

LINKS

Alois P. Heinz, Antidiagonals n = 0..15, flattened

Wikipedia, Pentomino

EXAMPLE

A(2,3) = A(3,2) = 7:

.___. .___. .___. .___. .___. .___. .___.

|_|_| | | | | | |_| |_| | | ._| |_. |

|_|_| | ._| |_. | | | | | | |_| |_| |

|_|_| |_|_| |_|_| |___| |___| |___| |___| .