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Search: id:A141114
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| A141114 |
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Those positive integers n where d(d(n)) is coprime to n, where d(n) is the number of divisors of n. |
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+0
3
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| 1, 3, 5, 7, 8, 9, 10, 11, 13, 14, 17, 19, 22, 23, 25, 26, 29, 31, 34, 35, 37, 38, 41, 43, 45, 46, 47, 49, 53, 55, 58, 59, 61, 62, 63, 65, 67, 71, 73, 74, 75, 77, 79, 81, 82, 83, 85, 86, 89, 91, 94, 95, 97, 99, 100, 101, 103, 105, 106, 107, 109, 113, 115, 117, 118, 119, 121
(list; graph; listen)
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OFFSET
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1,2
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LINKS
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Leroy Quet, Home Page (listed in lieu of email address)
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EXAMPLE
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26 has 4 divisors and 4 has 3 divisors. 3 is coprime to 26, so 26 is in the sequence.
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MATHEMATICA
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Select[Range[200], GCD[DivisorSigma[0, DivisorSigma[0, # ]], # ] == 1 &] - Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Jun 05 2008
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CROSSREFS
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Cf. A010553, A141113, A141115.
Sequence in context: A100318 A167707 A131903 this_sequence A136443 A020491 A047746
Adjacent sequences: A141111 A141112 A141113 this_sequence A141115 A141116 A141117
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet Jun 04 2008
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EXTENSIONS
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More terms from Stefan Steinerberger (stefan.steinerberger(AT)gmail.com), Jun 05 2008
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