a(n) is the concatenation of n n times, n-1 n-1 times, ..., 22, 1.

A300517

a(n) is the concatenation of n n times, n-1 n-1 times, ..., 22, 1.

Terms

    a(0) =1a(1) =221a(2) =333221a(3) =4444333221

External references