%I
%S 1,2,2,3,2,2,2,2,3,2,2,6,2,2,2,5,2,6,2,6,2,2,2,2,3,2,2,6,2,2,2,6,2,2,
%T 2,3,2,2,2,2,2,2,2,6,6,2,2,10,3,6,2,6,2,2,2,2,2,2,2,6,2,2,6,7,2,2,2,6,
%U 2,2,2,6,2,2,6,6,2,2,2,10,5,2,2,6,2,2,2,2,2,6,2,6,2,2,2,6,2,6,6,3,2,2,2,2,2
%N Largest squarefree number dividing the number of divisors n.
%H Antti Karttunen, <a href="/A152235/b152235.txt">Table of n, a(n) for n = 1..10000</a>
%H <a href="/index/Eu#epf">Index entries for sequences computed from exponents in factorization of n</a>
%F a(n) = rad(tau(n)) = A007947(A000005(n)).
%t f[n_] := Last@ Select[ Divisors@ DivisorSigma[0, n], SquareFreeQ@# &]; Array[f, 105] (* _Robert G. Wilson v_, Dec 23 2008 *)
%o (MAGMA) [ 1 ] cat [ &*[ k[1]: k in Factorization(NumberOfDivisors(n)) ]: n in [2..105] ]; // _Klaus Brockhaus_, Dec 03 2008
%o (PARI) for(n=1,50, print1(factorback(factorint(numdiv(n))[,1]), ", ")) \\ _G. C. Greubel_, Jul 13 2017; corrected by _Amiram Eldar_, Sep 01 2019 *)
%Y Cf. A000005, A007947.
%K easy,nonn
%O 1,2
%A _Giovanni Teofilatto_, Nov 30 2008
%E Extended by _Klaus Brockhaus_, Dec 03 2008
