Numbers k such that (199*10^k - 7)/3 is prime.

Terms

a(0) =1a(1) =4a(2) =16a(3) =25a(4) =27a(5) =39a(6) =109a(7) =117a(8) =720a(9) =989a(10) =1451a(11) =1477a(12) =1522a(13) =2242a(14) =2657a(15) =2694a(16) =2929a(17) =5927a(18) =7589a(19) =7844a(20) =9990a(21) =19475a(22) =43896a(23) =44304a(24) =95134a(25) =128343a(26) =129487