Number of powerful numbers that are not prime powers that do not exceed 10^n.

Terms

a(0) =0a(1) =0a(2) =3a(3) =28a(4) =133a(5) =510a(6) =1790a(7) =5997a(8) =19639a(9) =63541a(10) =204037a(11) =652173a(12) =2078320a(13) =6609816a(14) =20993381a(15) =66612867a(16) =211222374a(17) =669428537a(18) =2120835892a(19) =6717184256a(20) =21270247404a(21) =67341572823a(22) =213173925948a(23) =674739560651