Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, down, up, down, down, down.

A177583

Number of permutations of 2 copies of 1..n avoiding adjacent step pattern up, down, up, down, down, down.

Terms

    a(0) =1a(1) =6a(2) =90a(3) =2504a(4) =111312a(5) =7228080a(6) =645394636a(7) =75850937208

External references