Triangular numbers of the form p*w, where p is a prime number and w is a prime power (A025475).

Terms

a(0) =3a(1) =28a(2) =45a(3) =136a(4) =153a(5) =171a(6) =325a(7) =351a(8) =496a(9) =1431a(10) =3321a(11) =4753a(12) =7381a(13) =8128a(14) =13203a(15) =29161a(16) =31375a(17) =32896a(18) =56953a(19) =65341a(20) =118341a(21) =166753a(22) =195625a(23) =354061a(24) =780625a(25) =1063611a(26) =2390391a(27) =2883601a(28) =3544453a(29) =5649841