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Search: id:A064124
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| A064124 |
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Number of divisors of 7^n - 1 that are relatively prime to 7^m - 1 for all 0 < m < n. |
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+0
1
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| 4, 1, 2, 3, 2, 2, 4, 2, 4, 4, 4, 4, 2, 4, 4, 4, 4, 2, 4, 4, 2, 4, 8, 8, 4, 4, 16, 2, 8, 2, 8, 4, 8, 2, 4, 2, 8, 4, 8, 4, 8, 4, 4, 8, 4, 2, 4, 2, 16, 2, 16, 4, 8, 2, 2, 16, 8, 2, 16, 4, 16, 8, 2, 8, 32, 4, 16, 8, 8, 16
(list; graph; listen)
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OFFSET
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1,1
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LINKS
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Sam Wagstaff, Cunningham Project, Factorizations of 7^n-1, n odd, n<300
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MATHEMATICA
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a = {1}; Do[ d = Divisors[ 7^n - 1 ]; l = Length[ d ]; c = 0; k = 1; While[ k < l + 1, If[ Union[ GCD[ a, d[ [ k ] ] ] ] == {1}, c++ ]; k++ ]; Print[ c ]; a = Union[ Flatten[ Append[ a, Transpose[ FactorInteger[ 7^n - 1 ] ][ [ 1 ] ] ] ] ], {n, 1, 70} ]
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CROSSREFS
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Cf. A063982.
Adjacent sequences: A064121 A064122 A064123 this_sequence A064125 A064126 A064127
Sequence in context: A117021 A010473 A131100 this_sequence A106654 A090204 A072046
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KEYWORD
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nonn
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AUTHOR
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Robert G. Wilson v (rgwv(AT)rgwv.com), Sep 10 2001
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