Semiprimes s such that s-/+2 are primes.

Terms

a(0) =9a(1) =15a(2) =21a(3) =39a(4) =69a(5) =111a(6) =129a(7) =309a(8) =381a(9) =489a(10) =501a(11) =771a(12) =879a(13) =939a(14) =1011a(15) =1299a(16) =1569a(17) =2271a(18) =2391a(19) =2661a(20) =2859a(21) =3039a(22) =3189a(23) =3459a(24) =3849a(25) =3909a(26) =3921a(27) =4449a(28) =4791a(29) =4971