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A080403
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Numbers n such that both A000213(n) and A001157(n) are squarefree: sum of divisors and squares of divisors of n are squarefree.
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1
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1, 2, 4, 5, 8, 9, 13, 16, 18, 20, 25, 29, 37, 49, 50, 61, 64, 72, 73, 80, 101, 109, 113, 116, 117, 121, 122, 128, 137, 144, 148, 169, 173, 181, 200, 208, 218, 229, 242, 244, 261, 277, 281, 289, 292, 313, 317, 320, 325, 333, 353, 362, 373, 389, 397, 401, 404, 409
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OFFSET
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1,2
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LINKS
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MATHEMATICA
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Do[s1=MoebiusMu[DivisorSigma[1, n]]; s2=MoebiusMu[DivisorSigma[2, n]]; If[ !Equal[s1, 0]&&!Equal[s2, 0], Print[n]], {n, 1, 1000}]
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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