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A054985
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Composite numbers x such that sigma(x+120) = sigma(x)+120.
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2
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182, 203, 287, 350, 407, 558, 611, 731, 779, 803, 963, 1424, 1643, 2627, 2747, 3431, 3806, 4187, 4223, 5063, 6767, 7946, 8927, 9047, 11904, 12707, 12878, 15794, 18923, 20567, 27263, 31175, 32111, 34427, 43139, 43811, 45854, 50165, 52592, 57479
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OFFSET
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1,1
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COMMENTS
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LINKS
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EXAMPLE
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a(6)=558, sigma(558)+120=1248+120=1368=sigma(678)=sigma(558+120).
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MATHEMATICA
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Select[Range[60000], CompositeQ[#]&&DivisorSigma[1, #]+120 == DivisorSigma[ 1, #+120]&] (* _Harvey P. Dale_, Nov 25 2022 *)
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PROG
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(PARI) isok(n) = !isprime(n) && (sigma(n+120) == (sigma(n) + 120)); \\ _Michel Marcus_, Dec 31 2013
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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_Labos Elemer_, May 29 2000
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STATUS
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approved
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