Blum integers: numbers of the form p * q where p and q are distinct primes congruent to 3 (mod 4).

Terms

a(0) =21a(1) =33a(2) =57a(3) =69a(4) =77a(5) =93a(6) =129a(7) =133a(8) =141a(9) =161a(10) =177a(11) =201a(12) =209a(13) =213a(14) =217a(15) =237a(16) =249a(17) =253a(18) =301a(19) =309a(20) =321a(21) =329a(22) =341a(23) =381a(24) =393a(25) =413a(26) =417a(27) =437a(28) =453a(29) =469