Numbers k such that 3*10^k + 1 is prime.

Terms

a(0) =1a(1) =3a(2) =7a(3) =10a(4) =28a(5) =36a(6) =67a(7) =81a(8) =147a(9) =483a(10) =643a(11) =1020a(12) =1900a(13) =2620a(14) =10453a(15) =27720a(16) =52824a(17) =105589a(18) =111988a(19) =618853a(20) =665829