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 A080238 Largest squarefree number dividing sum of cubes of divisors of n. 1

%I

%S 1,3,14,73,42,42,86,195,757,42,222,1022,2198,258,42,4681,546,2271,70,

%T 3066,602,222,78,2730,15751,6594,5110,6278,8130,42,266,4161,1554,546,

%U 1806,55261,50654,210,2198,2730,22974,1806,39754,16206,31794,78,4326

%N Largest squarefree number dividing sum of cubes of divisors of n.

%H Amiram Eldar, <a href="/A080238/b080238.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A007947(A001158(n)).

%e n=12: sigma_3(12) = 1 + 8 + 27 + 64 + 216 + 1728 = 2044, sqf-kernel = 1022 = 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[3, w]], {w, 1, 100}]

%Y Cf. A000213, A001157, A007947.

%K nonn

%O 1,2

%A _Labos Elemer_, Mar 19 2003

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Last modified January 22 13:41 EST 2020. Contains 331149 sequences. (Running on oeis4.)