Number of n-digit primes whose digits are all primes.

Terms

a(0) =4a(1) =4a(2) =15a(3) =38a(4) =128a(5) =389a(6) =1325a(7) =4643a(8) =16623a(9) =59241a(10) =214432a(11) =781471a(12) =2884201a(13) =10687480a(14) =39838489a(15) =149172297a(16) =560795383a(17) =2115430020