1/3 the number of (n+1)X7 0..2 arrays with every 2X2 subblock having at least two equal elements connected horizontally or vertically.

A184373

1/3 the number of (n+1)X7 0..2 arrays with every 2X2 subblock having at least two equal elements connected horizontally or vertically.

Terms

    a(0) =420633a(1) =281803871a(2) =185547841629

External references