Primes which are triangular numbers plus 3.

Terms

a(0) =3a(1) =13a(2) =31a(3) =139a(4) =193a(5) =409a(6) =499a(7) =823a(8) =1381a(9) =1543a(10) =2083a(11) =2281a(12) =3163a(13) =3919a(14) =6673a(15) =7753a(16) =9319a(17) =9733a(18) =17581a(19) =19309a(20) =21739a(21) =22369a(22) =24979a(23) =27031a(24) =27733a(25) =30631a(26) =39343a(27) =40189a(28) =51043a(29) =53959