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A014946
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Numbers k that divide 6^k-1.
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16
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1, 5, 25, 125, 625, 1555, 3125, 7775, 15625, 38875, 78125, 194375, 390625, 483605, 971875, 1953125, 2418025, 4859375, 9673655, 9765625, 12090125, 24296875, 48368275, 48828125, 60450625, 120909025, 121484375, 150401155, 241841375
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OFFSET
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1,2
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COMMENTS
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Includes all powers of 5. If a term such as 1555 = 5*311 occurs, so does any number of the form 5^a * 311^b for a>3.
All terms that are not powers of 5 are divisible by 5 and 311.
Prime divisors of a(n) are {5, 311, 6221, 15551, 155501, ...}. (End)
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LINKS
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MATHEMATICA
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Select[ Range[ 5*10^7], PowerMod[6, #, # ] == 1 & ]
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PROG
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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