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

Terms

a(0) =3a(1) =12a(2) =42a(3) =125a(4) =608a(5) =2427a(6) =10081a(7) =43568a(8) =197823a(9) =873432a(10) =3978580a(11) =18159630a(12) =83753054a(13) =387670103a(14) =1811802273a(15) =8451565541a(16) =39790817677