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

A145237

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

Terms

    a(0) =1a(1) =4a(2) =24a(3) =216a(4) =2952a(5) =61488a(6) =1957392a(7) =95392296a(8) =7125411888a(9) =816458567400

External references