a(n) = 2*(10^(2n+1)-1)/9 + 10^n.

A332123

a(n) = 2*(10^(2n+1)-1)/9 + 10^n.

Terms

    a(0) =3a(1) =232a(2) =22322a(3) =2223222a(4) =222232222a(5) =22222322222

External references