Number of odd primes less than n-th odd composite number.

Terms

a(0) =3a(1) =5a(2) =7a(3) =8a(4) =8a(5) =10a(6) =10a(7) =11a(8) =13a(9) =14a(10) =14a(11) =15a(12) =15a(13) =17a(14) =17a(15) =18a(16) =20a(17) =20a(18) =21a(19) =22a(20) =22a(21) =23a(22) =23a(23) =23a(24) =24a(25) =26a(26) =28a(27) =29a(28) =29a(29) =29