Number of subsets of {1,.., n} containing exactly one prime.

Terms

a(0) =0a(1) =2a(2) =4a(3) =8a(4) =12a(5) =24a(6) =32a(7) =64a(8) =128a(9) =256a(10) =320a(11) =640a(12) =768a(13) =1536a(14) =3072a(15) =6144a(16) =7168a(17) =14336a(18) =16384a(19) =32768a(20) =65536a(21) =131072a(22) =147456a(23) =294912a(24) =589824a(25) =1179648a(26) =2359296a(27) =4718592a(28) =5242880a(29) =10485760