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

A177316

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

Terms

    a(0) =1a(1) =2a(2) =26a(3) =506a(4) =11482a(5) =284002a(6) =7426610a(7) =201922730a(8) =5650739930a(9) =161686253810

External references