1/3 of the number of 3-colorings of an n X n array symmetric about both diagonal and antidiagonal.

A145238

1/3 of the number of 3-colorings of an n X n array symmetric about both diagonal and antidiagonal.

Terms

    a(0) =1a(1) =2a(2) =8a(3) =24a(4) =144a(5) =648a(6) =5904a(7) =40392a(8) =561744a(9) =5871528a(10) =124982208a(11) =2000735640a(12) =65289654720

External references