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A326128 a(n) = n - A007913(n), where A007913 gives the squarefree part of n.

%I A326128 #14 Mar 21 2024 08:35:56
%S A326128 0,0,0,3,0,0,0,6,8,0,0,9,0,0,0,15,0,16,0,15,0,0,0,18,24,0,24,21,0,0,0,
%T A326128 30,0,0,0,35,0,0,0,30,0,0,0,33,40,0,0,45,48,48,0,39,0,48,0,42,0,0,0,
%U A326128 45,0,0,56,63,0,0,0,51,0,0,0,70,0,0,72,57,0,0,0,75,80,0,0,63,0,0,0,66,0,80,0,69,0,0,0,90,0,96,88,99,0,0,0,78,0
%N A326128 a(n) = n - A007913(n), where A007913 gives the squarefree part of n.
%H A326128 Antti Karttunen, <a href="/A326128/b326128.txt">Table of n, a(n) for n = 1..16384</a>
%H A326128 Antti Karttunen, <a href="/A326128/a326128.txt">Data supplement: n, a(n) computed for n = 1..65537</a>.
%F A326128 a(n) = n - A007913(n).
%F A326128 a(n) = A326127(n) + A033879(n).
%F A326128 a(n) >= A066503(n).
%F A326128 a(n) = A007913(n) * A336642(n). - _Antti Karttunen_, Jul 28 2020
%F A326128 Sum_{k=1..n} a(k) ~ c * n^2, where c = 1/2 - Pi^2/30 = 0.171013... . - _Amiram Eldar_, Mar 21 2024
%t A326128 f[p_, e_] := p^Mod[e, 2]; a[n_] := n - Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* _Amiram Eldar_, Mar 21 2024 *)
%o A326128 (PARI) A326128(n) = (n-core(n));
%Y A326128 Cf. A007913, A033879, A326126, A326127, A326129, A336642.
%Y A326128 Cf. also A066503.
%K A326128 nonn
%O A326128 1,4
%A A326128 _Antti Karttunen_, Jun 09 2019