n such that (1+2*7^n)/3 is prime.

Terms

a(0) =1a(1) =3a(2) =4a(3) =15a(4) =24a(5) =58a(6) =168a(7) =234a(8) =324a(9) =375a(10) =3327a(11) =5788a(12) =8344a(13) =15039a(14) =59116a(15) =62620