1/4 of the number of 4-colorings of an n X n array symmetric about main diagonal.
A145240
1/4 of the number of 4-colorings of an n X n array symmetric about main diagonal.
Terms
- a(0) =1a(1) =9a(2) =189a(3) =9261a(4) =1059723a(5) =283237101a(6) =176834417193
External references
- oeis: A145240