Odd triangular numbers with prime indices.

Terms

a(0) =3a(1) =15a(2) =91a(3) =153a(4) =435a(5) =703a(6) =861a(7) =1431a(8) =1891a(9) =2701a(10) =4005a(11) =4753a(12) =5151a(13) =5995a(14) =6441a(15) =9453a(16) =11175a(17) =12403a(18) =15051a(19) =16471a(20) =18721a(21) =19503a(22) =26335a(23) =27261a(24) =29161a(25) =33153a(26) =36315a(27) =38503a(28) =39621a(29) =43071