Numbers k such that 10^k - 401 is prime.

Terms

a(0) =3a(1) =6a(2) =9a(3) =11a(4) =12a(5) =25a(6) =47a(7) =166a(8) =222a(9) =234a(10) =352a(11) =407a(12) =515a(13) =646a(14) =1161a(15) =2475a(16) =4329a(17) =7191a(18) =12894a(19) =16007a(20) =25819a(21) =67579a(22) =88457a(23) =117135