Number of permutations of n copies of 1..4 with all adjacent differences <= 2 in absolute value.

A177322

Number of permutations of n copies of 1..4 with all adjacent differences <= 2 in absolute value.

Terms

    a(0) =1a(1) =12a(2) =660a(3) =51240a(4) =4635540a(5) =457507512a(6) =47768769048

External references