Number of up-down sequences with 3 copies each of 1,2,...,n.

A276636

Number of up-down sequences with 3 copies each of 1,2,...,n.

Terms

    a(0) =1a(1) =0a(2) =1a(3) =12a(4) =761a(5) =87336a(6) =18528505a(7) =6376563600

External references