A219975 Number of tilings of an n X n square using straight (3 X 1) trominoes and 2 X 2 tiles.

1, 0, 1, 2, 3, 28, 267, 2744, 66653, 2766100, 141365332, 13305552648, 2149055591278

Offset

0,4

Links

Table of n, a(n) for n=0..12.

Example

a(4) = 3, because there are 3 tilings of a 4 X 4 square using straight (3 X 1) trominoes and 2 X 2 tiles:
  ._._____.  ._____._.  ._._._._.
  | |_____|  |_____| |  | . | . |
  | | . | |  | | . | |  |___|___|
  |_|___| |  | |___|_|  | . | . |
  |_____|_|  |_|_____|  |___|___|  .

Crossrefs

Main diagonal of A219967.

Cf. A233807.

Sequence in context: A371115 A206592 A126266 * A319146 A206591 A003017

Adjacent sequences: A219972 A219973 A219974 * A219976 A219977 A219978

Keyword

nonn,more

Author

Alois P. Heinz, Dec 02 2012

Extensions

a(12) from Alois P. Heinz, Sep 24 2014

Status

approved