Semiprimes of the form n*(3*n-1)/2.

Terms

a(0) =22a(1) =35a(2) =51a(3) =145a(4) =247a(5) =287a(6) =1247a(7) =1717a(8) =2147a(9) =2501a(10) =3151a(11) =4187a(12) =5017a(13) =7957a(14) =11051a(15) =13207a(16) =15251a(17) =16801a(18) =17767a(19) =20827a(20) =26867a(21) =33227a(22) =49051a(23) =63551a(24) =68587a(25) =71177a(26) =76501a(27) =81317a(28) =96647a(29) =112477