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a(n) = (n-rad(n)) / core(n), where rad(n) and core(n) give the squarefree kernel and squarefree part of n, respectively.
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%I #13 Dec 30 2021 12:18:56

%S 0,0,0,2,0,0,0,3,6,0,0,2,0,0,0,14,0,6,0,2,0,0,0,3,20,0,8,2,0,0,0,15,0,

%T 0,0,30,0,0,0,3,0,0,0,2,6,0,0,14,42,20,0,2,0,8,0,3,0,0,0,2,0,0,6,62,0,

%U 0,0,2,0,0,0,33,0,0,20,2,0,0,0,14,78,0,0,2,0,0,0,3,0,6,0,2,0,0,0,15,0,42,6,90,0,0,0,3,0

%N a(n) = (n-rad(n)) / core(n), where rad(n) and core(n) give the squarefree kernel and squarefree part of n, respectively.

%H Antti Karttunen, <a href="/A336644/b336644.txt">Table of n, a(n) for n = 1..16384</a>

%H Antti Karttunen, <a href="/A336644/a336644.txt">Data supplement: n, a(n) computed for n = 1..65537</a>

%F a(n) = A066503(n) / A007913(n) = (n-A007947(n)) / A007913(n).

%F a(n) = A008833(n) - A336643(n).

%o (PARI) A336644(n) = ((n-factorback(factorint(n)[, 1])) / core(n));

%o (Python)

%o from math import prod

%o from sympy.ntheory.factor_ import primefactors, core

%o def A336644(n): return (n-prod(primefactors(n)))//core(n) # _Chai Wah Wu_, Dec 30 2021

%Y Cf. A007913, A007947, A008833, A066503, A336642, A336643.

%K nonn

%O 1,4

%A _Antti Karttunen_, Jul 28 2020