Number of odd composites <= 10^n.

Terms

a(0) =1a(1) =25a(2) =332a(3) =3771a(4) =40408a(5) =421502a(6) =4335421a(7) =44238545a(8) =449152466a(9) =4544947489a(10) =45881945187a(11) =462392087982