Numbers k such that 4*5^k + 1 is prime.

Terms

a(0) =0a(1) =2a(2) =6a(3) =18a(4) =50a(5) =290a(6) =2582a(7) =20462a(8) =23870a(9) =26342a(10) =31938a(11) =38122a(12) =65034a(13) =70130a(14) =245538a(15) =851878a(16) =1052422a(17) =1496566a(18) =5380542a(19) =8431178