Number of 2-colored patterns on an n X n board.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =8a(5) =24a(6) =108a(7) =640a(8) =4492a(9) =36336a(10) =329900a(11) =3326788a(12) =36846288a(13) =444790512a(14) =5811886656a(15) =81729688428