Numbers k such that (k^2 + k + 1)/3 is prime.

Terms

a(0) =4a(1) =7a(2) =10a(3) =13a(4) =19a(5) =28a(6) =31a(7) =34a(8) =40a(9) =43a(10) =52a(11) =70a(12) =73a(13) =76a(14) =82a(15) =85a(16) =91a(17) =97a(18) =103a(19) =112a(20) =115a(21) =124a(22) =127a(23) =136a(24) =145a(25) =148a(26) =157a(27) =166a(28) =175a(29) =187