The number of primes less than 10^n whose digital root (A038194) is also prime.

A079155

The number of primes less than 10^n whose digital root (A038194) is also prime.

Terms

    a(0) =4a(1) =15a(2) =85a(3) =619a(4) =4800a(5) =39266a(6) =332276a(7) =2880818a(8) =25423985a(9) =227527467

External references