Numbers k such that 5^k - 4 is prime.

Terms

a(0) =5a(1) =7a(2) =15a(3) =47a(4) =81a(5) =115a(6) =267a(7) =285a(8) =7641a(9) =19089a(10) =25831a(11) =32115a(12) =59811a(13) =70155a(14) =178715