1/25 the number of (n+1) X 3 0..4 arrays with every 2 X 2 subblock having equal diagonal elements or equal antidiagonal elements.

A203650

1/25 the number of (n+1) X 3 0..4 arrays with every 2 X 2 subblock having equal diagonal elements or equal antidiagonal elements.

Terms

    a(0) =81a(1) =1517a(2) =28057a(3) =519445a(4) =9616161a(5) =178019197a(6) =3295578857a(7) =61009378085

External references