1/4 of the number of 4-colorings of an n X n array symmetric about both diagonal and antidiagonal.
A145241
1/4 of the number of 4-colorings of an n X n array symmetric about both diagonal and antidiagonal.
Terms
- a(0) =1a(1) =3a(2) =27a(3) =189a(4) =3969a(5) =64827a(6) =3179169a(7) =121272795a(8) =13891861179
External references
- oeis: A145241