Number of odd squarefree semiprimes (A046388) < 2^n.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =2a(5) =8a(6) =20a(7) =46a(8) =96a(9) =197a(10) =404a(11) =798a(12) =1599a(13) =3134a(14) =6169a(15) =12093a(16) =23640a(17) =46199a(18) =90180a(19) =176198a(20) =343927a(21) =671783a(22) =1312304a(23) =2564485a(24) =5012807a(25) =9803883a(26) =19181677a(27) =37545265a(28) =73524262a(29) =144038812