Smaller member of a twin prime pair with a triangular sum.

Terms

a(0) =17a(1) =59a(2) =137a(3) =149a(4) =1277a(5) =1619a(6) =2729a(7) =4127a(8) =6359a(9) =11717a(10) =13397a(11) =17489a(12) =20807a(13) =23027a(14) =28307a(15) =29669a(16) =51869a(17) =61379a(18) =69827a(19) =73847a(20) =78539a(21) =92567a(22) =97499a(23) =115769a(24) =138569a(25) =166667a(26) =176609a(27) =193379a(28) =200927a(29) =258317