1/24 the number of (n+1)X4 0..3 arrays with every 2X2 subblock containing exactly three distinct values.

A183588

1/24 the number of (n+1)X4 0..3 arrays with every 2X2 subblock containing exactly three distinct values.

Terms

    a(0) =520a(1) =27380a(2) =1427084a(3) =74491726a(4) =3887550226a(5) =202888369698

External references