a(n) = 10^(2*n+2) + 111*10^n + 1.

A344423

a(n) = 10^(2*n+2) + 111*10^n + 1.

Terms

    a(0) =212a(1) =11111a(2) =1011101a(3) =100111001a(4) =10001110001

External references