Numbers k such that (k^2 + k + 1)/21 is prime.

Terms

a(0) =16a(1) =25a(2) =37a(3) =46a(4) =58a(5) =88a(6) =109a(7) =130a(8) =142a(9) =151a(10) =184a(11) =193a(12) =205a(13) =247a(14) =268a(15) =298a(16) =310a(17) =319a(18) =331a(19) =340a(20) =382a(21) =394a(22) =403a(23) =415a(24) =424a(25) =457a(26) =478a(27) =487a(28) =541a(29) =550