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Search: id:A072303
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| A072303 |
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Numbers n for which n is congruent to n^2 modulo Phi(n). |
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+0
1
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| 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12, 13, 16, 17, 18, 19, 21, 23, 24, 25, 27, 28, 29, 31, 32, 36, 37, 41, 43, 47, 48, 49, 53, 54, 59, 61, 64, 67, 71, 72, 73, 79, 81, 83, 89, 96, 97, 101, 103, 107, 108, 109, 112, 113, 121, 125, 127, 128, 131, 137, 139, 144, 149, 151, 157
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Or, numbers n such that phi(n) divides n*(n-1). - Mohammed Bouayoun (mohammed.bouayoun(AT)sanef.com), Apr 14 2006
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FORMULA
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Numbers n for which n is congruent to n^2 modulo Phi(n), where Phi(n) is the Euler totient function.
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EXAMPLE
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9 is in the sequence because Phi(9) = 6. 9 % 6 = 3, and 9^2 % 6 = 3. But 10 is not in the sequence because Phi(10) = 4, and 10 % 4 = 6, and 10^2 % 4 = 0.
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CROSSREFS
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Cf. A000010, A068494.
Sequence in context: A037173 A091897 A055201 this_sequence A081061 A141807 A072495
Adjacent sequences: A072300 A072301 A072302 this_sequence A072304 A072305 A072306
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KEYWORD
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easy,nonn
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AUTHOR
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Igor Naverniouk (igor(AT)lexansoft.com), Jul 14 2002
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