Primes of the form floor(k*(k+1)*Pi/2), k>=0, where Pi = 3.1415.. = A000796.

Terms

a(0) =3a(1) =31a(2) =47a(3) =113a(4) =659a(5) =1021a(6) =1187a(7) =1979a(8) =2971a(9) =3251a(10) =5749a(11) =9679a(12) =10433a(13) =14627a(14) =20593a(15) =22807a(16) =23957a(17) =35107a(18) =39461a(19) =55813a(20) =58207a(21) =109063a(22) =152417a(23) =157349a(24) =201881a(25) =227419a(26) =244463a(27) =262121a(28) =292469a(29) =295187