DivisorSum[DivisorSigma[1, Subscript[d, j]] DivisorSigma[1, n/Subscript[d, j]], {Subscript[d, j], n}] == DivisorSum[d DivisorSigma[0, Subscript[d, j]] DivisorSigma[0, n/Subscript[d, j]], {Subscript[d, j], n}] /; Element[Subscript[d, j], Divisors[n]]

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2001-10-29