%I #13 Aug 01 2019 11:33:17
%S 1,5,10,21,26,10,10,85,91,130,122,210,170,10,130,341,290,455,362,546,
%T 10,610,530,170,651,170,410,210,842,130,962,1365,610,290,130,273,1370,
%U 1810,170,2210,58,10,370,2562,182,530,2210,3410,2451,3255,290,3570,2810,410
%N Largest squarefree number dividing sum of squares of divisors of n.
%H Amiram Eldar, <a href="/A080399/b080399.txt">Table of n, a(n) for n = 1..10000</a>
%F a(n) = A007947(A001157(n)).
%e sigma_2(12) = 1 + 4 + 9 + 16 + 36 + 144 = 210, sqf-kernel = 210 = a(12).
%t ffi[x_] := Flatten[FactorInteger[x]] lf[x_] := Length[FactorInteger[x]] ba[x_] := Table[Part[ffi[x], 2*w-1], {w, 1, lf[x]}] cor[x_] := Apply[Times, ba[x]] Table[cor[DivisorSigma[2, w]], {w, 1, 100}]
%Y Cf. A000213, A001157, A007947.
%K nonn
%O 1,2
%A _Labos Elemer_, Mar 19 2003