Numbers that are divisible only by primes congruent to 3 mod 4.

Terms

a(0) =1a(1) =3a(2) =7a(3) =9a(4) =11a(5) =19a(6) =21a(7) =23a(8) =27a(9) =31a(10) =33a(11) =43a(12) =47a(13) =49a(14) =57a(15) =59a(16) =63a(17) =67a(18) =69a(19) =71a(20) =77a(21) =79a(22) =81a(23) =83a(24) =93a(25) =99a(26) =103a(27) =107a(28) =121a(29) =127