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%I #23 Feb 16 2021 04:31:02
%S 0,0,0,0,0,0,0,0,0,0,0,1,1,1,1,1,1,2,2,3,3,3,3,3,3,3,3,4,4,4,4,4,4,4,
%T 4,4,4,4,4,4,4,4,4,5,6,6,6,6,6,7,7,8,8,8,8,8,8,8,8,9,9,9,10,10,10,10,
%U 10,11,11,11,11,11,11,11,12,13,13,13,13,13,13,13,13,14,14,14,14,14,14,15
%N Number of cubefree numbers <= n which are nonsquares having exactly one square in their factorization.
%H Harvey P. Dale, <a href="/A072375/b072375.txt">Table of n, a(n) for n = 1..1000</a>
%F a(n) ~ c * n, where c = (6/Pi^2) * Sum_{p prime} 1/(p*(p+1)) = 0.200755... (A271971). - _Amiram Eldar_, Feb 16 2021
%t cfnsQ[n_]:=Module[{f=FactorInteger[n][[All,2]]},Max[f]<3&&Count[f,2] == 1&&!IntegerQ[Sqrt[n]]]; Accumulate[Table[If[cfnsQ[n],1,0],{n,100}]] (* _Harvey P. Dale_, May 24 2017 *)
%Y Cf. A072357, A072358, A060431, A271971.
%K nonn
%O 1,18
%A _Reinhard Zumkeller_, Jul 19 2002
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