Number of perfect powers k which are not prime powers, and 1 < k < 10^n.

Terms

a(0) =0a(1) =1a(2) =14a(3) =72a(4) =257a(5) =873a(6) =2838a(7) =9085a(8) =28979a(9) =92145a(10) =292832a(11) =930124a(12) =2953569a(13) =9376798a(14) =29760901a(15) =94434276a(16) =299569798a(17) =950072891a(18) =3012393832a(19) =9549260877a(20) =30264906899a(21) =95902117819a(22) =303839485659a(23) =962486295193