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Search: id:A080403
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| A080403 |
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Numbers n such that both A000213(n) and A001157(n) are square-free: sum of divisors and squares of divisors of n are square-free. |
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+0
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
(list; graph; listen)
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OFFSET
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1,2
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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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Cf. A001157, A000213, A065300, A080401, A080402.
Sequence in context: A143989 A064573 A065300 this_sequence A092739 A101394 A095031
Adjacent sequences: A080400 A080401 A080402 this_sequence A080404 A080405 A080406
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KEYWORD
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easy,nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Mar 19 2003
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