a(1) = 1, a(n)= number obtained by replacing each digit of a(n-1) with four times its value.

A061580

a(1) = 1, a(n)= number obtained by replacing each digit of a(n-1) with four times its value.

Terms

    a(0) =1a(1) =4a(2) =16a(3) =424a(4) =16816a(5) =42432424

External references