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%I #14 Jan 22 2022 00:07:54
%S 6,15,10,2,6,35,6,2,2,21,6,2,6,15,14,2,6,2,6,2,10,15,6,2,2,15,2,2,6,
%T 77,6,2,10,15,6,2,6,15,10,2,6,55,6,2,2,15,6,2,2,2,10,2,6,2,6,2,10,15,
%U 6,2,6,15,2,2,6,35,6,2,10,33,6,2,6,15,2,2,6,35,6,2,2,15,6,2,6,15,10,2,6,2,6,2
%N Smallest k>1 such that mu(n*k) = mu(n), where mu=A008683.
%C a(n) = A123624(n) / n.
%C From _Robert Israel_, Apr 02 2017: (Start)
%C If n is squarefree, a(n) is the product of the least two primes coprime to n.
%C Otherwise a(n) = 2. (End)
%H R. Zumkeller, <a href="/A123623/b123623.txt">Table of n, a(n) for n = 1..10000</a>
%p a:= proc(n) local r,p,count;
%p if not numtheory:-issqrfree(n) then return 2 fi;
%p r:= 1; count:= 0; p:= 1;
%p do
%p p:= nextprime(p);
%p if n mod p > 0 then
%p count:= count+1;
%p r:= r*p;
%p if count = 2 then return r fi
%p fi
%p od
%p end proc:
%p map(a, [$1..1000]); # _Robert Israel_, Apr 02 2017
%t a[n_] := Module[{r = 1, p = 1, count = 0}, If[!SquareFreeQ[n], Return[2]]; While[True, p = NextPrime[p]; If[Mod[n, p] > 0, count++; r = r*p; If[count == 2, Return[r]]]]]; Array[a, 100] (* _Jean-François Alcover_, Feb 13 2018, after _Robert Israel_ *)
%Y Cf. A093316.
%K nonn
%O 1,1
%A _Reinhard Zumkeller_, Oct 03 2006
%E Name corrected by _Robert Israel_, Apr 02 2017
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