1/4 the number of (n+1)X4 0..3 arrays with every 2X2 subblock having at least two equal elements connected horizontally or vertically.

A184147

1/4 the number of (n+1)X4 0..3 arrays with every 2X2 subblock having at least two equal elements connected horizontally or vertically.

Terms

    a(0) =5695a(1) =584143a(2) =58656073a(3) =5910714349a(4) =595270788529

External references