Semiprimes in A103379.

Terms

a(0) =4a(1) =9a(2) =15a(3) =21a(4) =33a(5) =38a(6) =58a(7) =65a(8) =86a(9) =106a(10) =121a(11) =129a(12) =265a(13) =511a(14) =2047a(15) =2049a(16) =4097a(17) =4109a(18) =17855a(19) =19857a(20) =32663a(21) =34709a(22) =104739a(23) =130393a(24) =131889a(25) =140474a(26) =220918a(27) =262978a(28) =266174a(29) =274759