1/4 the number of (n+1) X 3 0..3 arrays with every 2 X 2 subblock having at least two equal elements connected horizontally or vertically.

A184146

1/4 the number of (n+1) X 3 0..3 arrays with every 2 X 2 subblock having at least two equal elements connected horizontally or vertically.

Terms

    a(0) =499a(1) =17203a(2) =584143a(3) =19882711a(4) =676507975a(5) =23019453235a(6) =783273204631

External references