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Search: id:A060678
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| A060678 |
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Numbers n such that sigma (x) = n has exactly 11 solutions. |
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| 576, 1296, 2976, 3168, 3648, 3720, 4788, 4896, 5544, 6300, 9000, 9840, 10656, 11808, 12528, 13020, 13320, 14760, 15456, 16740, 17920, 18288, 18576, 19344, 19840, 20400, 21280, 22800, 23296, 24300, 26712, 26928, 27552, 27936, 28392
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OFFSET
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1,1
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EXAMPLE
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576 = sigma(210) = sigma(282) = sigma(310) = sigma(322) = sigma(345) = sigma(357) = sigma(382) = sigma(385) = sigma(497) = sigma(517) = sigma(527).
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MATHEMATICA
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a = Table[ 0, {30000} ]; Do[ s = DivisorSigma[ 1, n ]; If[ s < 30001, a[ [ s ] ]++ ], {n, 1, 30000} ]; Select[ Range[ 30000 ], a[ [ # ] ] == 11 & ]
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CROSSREFS
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Cf. A007370, A007371, A007372.
Sequence in context: A109101 A064253 A069266 this_sequence A137484 A064254 A067225
Adjacent sequences: A060675 A060676 A060677 this_sequence A060679 A060680 A060681
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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), Apr 18 2001
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