Number of permutations of 4 copies of 1..n avoiding adjacent step pattern up, down, down, up.

A177642

Number of permutations of 4 copies of 1..n avoiding adjacent step pattern up, down, down, up.

Terms

    a(0) =1a(1) =70a(2) =28854a(3) =39663852a(4) =137560321238

External references