%I #16 Dec 16 2023 09:02:47
%S 15,21,39,57,65,91,95,133
%N Composite numbers c such that pi(c) is the product of pi applied to the distinct prime factors of c.
%C Prime numbers trivially satisfy this property and so are excluded.
%e 15 is a term since its distinct prime factors are 3,5 and pi(15) = pi(3)*pi(5).
%t Select[Range[2,10000], ! PrimeQ[#] && Times @@ PrimePi[Transpose[FactorInteger[#]][[1]]] == PrimePi[#] &]
%Y Cf. A000720, A002808, A027748, A156061, A235623.
%K nonn,fini,full
%O 1,1
%A _Tanya Khovanova_, Nov 04 2023