1/4 of the number of 4-colorings of an n X n array symmetric under 180 degree rotation.
A145242
1/4 of the number of 4-colorings of an n X n array symmetric under 180 degree rotation.
Terms
- a(0) =1a(1) =3a(2) =51a(3) =813a(4) =75351a(5) =6514173a(6) =3287790591
External references
- oeis: A145242