Primes of the form (1 + k + k^3)/3.

Terms

a(0) =23a(1) =337a(2) =2293a(3) =3557a(4) =9941a(5) =21347a(6) =39233a(7) =87403a(8) =251221a(9) =333367a(10) =895253a(11) =1080647a(12) =1217473a(13) =1696207a(14) =2076563a(15) =2626933a(16) =2999707a(17) =4493837a(18) =6203297a(19) =6857033a(20) =8045953a(21) =8299127a(22) =8821297a(23) =11442817a(24) =13807361a(25) =14538187a(26) =17298497a(27) =21333467