a(n) = 3^(2^n) (or: write in base 3, read in base 9).

A011764

a(n) = 3^(2^n) (or: write in base 3, read in base 9).

Terms

    a(0) =3a(1) =9a(2) =81a(3) =6561a(4) =43046721

External references