Heptagonal numbers (A000566) that are semiprimes (A001358).

Terms

a(0) =34a(1) =55a(2) =235a(3) =403a(4) =469a(5) =697a(6) =1177a(7) =1651a(8) =2059a(9) =2839a(10) =4141a(11) =5221a(12) =6943a(13) =9211a(14) =9517a(15) =13213a(16) =13579a(17) =21949a(18) =23377a(19) =25351a(20) =29539a(21) =31753a(22) =34633a(23) =37027a(24) =53071a(25) =62173a(26) =68641a(27) =74563a(28) =78943a(29) =93799