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%I #16 Jun 26 2022 09:17:14
%S 2,3,4,4,6,6,8,8,9,9,11,11,11,12,12,14,15,15,16,16,16,18,18,19,21,21,
%T 22,23,23,23,24,24,24,24,27,29,30,30,30,30,30,30,31,32,32,34,34,34,34,
%U 34,36,37,37,37,38,39,40,40,42,42,42,44,46,46,46,46,46,46,47,47,47,47,47
%N Number of primes < semiprime(n).
%F a(n) = A000720(A001358(n)).
%t PrimePi@Select[Range@218, Plus @@ Last /@ FactorInteger@# == 2 &] (* _Robert G. Wilson v_, Jan 10 2006 *)
%t PrimePi/@Select[Range[300],PrimeOmega[#]==2&] (* _Harvey P. Dale_, Nov 16 2014 *)
%Y Cf. A122489.
%Y Partial sums of A176451.
%K nonn
%O 1,1
%A _Giovanni Teofilatto_, Nov 27 2005
%E More terms from _Robert G. Wilson v_, Lambert Herrgesell (zero815(AT)googlemail.com) and _Matthew Conroy_, Dec 16 2005
%E Entry revised by _Ray Chandler_, Sep 20 2006
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