Numbers k such that 20^k - 3 is prime.

Terms

a(0) =1a(1) =2a(2) =5a(3) =7a(4) =9a(5) =11a(6) =15a(7) =37a(8) =59a(9) =119a(10) =154a(11) =439a(12) =745a(13) =799a(14) =1260a(15) =1444a(16) =3306a(17) =8890a(18) =14604a(19) =15869a(20) =20195a(21) =99055a(22) =186554a(23) =396120