Number of powerful numbers not exceeding 2^n.

Terms

a(0) =1a(1) =1a(2) =2a(3) =3a(4) =5a(5) =8a(6) =11a(7) =18a(8) =26a(9) =38a(10) =55a(11) =80a(12) =116a(13) =166a(14) =240a(15) =345a(16) =497a(17) =710a(18) =1016a(19) =1453a(20) =2073a(21) =2955a(22) =4211a(23) =5992a(24) =8523a(25) =12111a(26) =17202a(27) =24423a(28) =34648a(29) =49152