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A240597
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Numbers k such that sigma(k) == k (mod 9).
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1
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1, 15, 24, 42, 60, 64, 69, 78, 90, 100, 114, 123, 133, 147, 153, 177, 186, 198, 222, 231, 240, 258, 259, 270, 276, 288, 289, 306, 339, 360, 366, 393, 402, 403, 414, 429, 438, 447, 459, 474, 477, 492, 495, 501, 507, 511, 522, 582, 588, 594, 600
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OFFSET
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1,2
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COMMENTS
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That is, numbers k that satisfy the following:
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LINKS
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FORMULA
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EXAMPLE
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sigma(15) = 24. 24 == 15 (mod 9), therefore 15 is in the sequence.
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MATHEMATICA
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Select[Range[1000], Mod[#, 9]==Mod[DivisorSigma[1, #], 9]&]
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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STATUS
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approved
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