Numbers k such that 7^k + 4 is prime.

Terms

a(0) =0a(1) =1a(2) =2a(3) =3a(4) =5a(5) =7a(6) =9a(7) =14a(8) =23a(9) =129a(10) =198a(11) =235a(12) =275a(13) =630a(14) =870a(15) =1033a(16) =1290a(17) =3293a(18) =3458a(19) =11466a(20) =13885a(21) =25893a(22) =32186a(23) =33139a(24) =58125a(25) =78929a(26) =97197a(27) =121933a(28) =128422a(29) =442674