Concatenation of the numbers from 1 to n with numbers from n down to 1.

A259937

Concatenation of the numbers from 1 to n with numbers from n down to 1.

Terms

    a(0) =11a(1) =1221a(2) =123321a(3) =12344321a(4) =1234554321a(5) =123456654321

External references