Primes of the form (5^k-1)/4 or (5^k+3)/4.

A088554

Primes of the form (5^k-1)/4 or (5^k+3)/4.

Terms

    a(0) =2a(1) =7a(2) =31a(3) =157a(4) =3907a(5) =19531a(6) =2441407a(7) =12207031a(8) =61035157a(9) =305175781

External references