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A275370
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Odd numbers n such that sigma(n) = sigma(2*n-1).
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2
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1, 13545, 57645, 116865, 1440495, 7029855, 8596455, 27361125, 41100345, 48289185, 56122185, 77560065, 103225185, 134813385, 146591235, 163817745, 188358885, 198748305, 242668335, 269436375, 352094715, 358841385, 535135965, 563911335, 636719265, 712457655, 724692045
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OFFSET
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1,2
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COMMENTS
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The smallest term that is not divisible by 5 is 1577106531.
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LINKS
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EXAMPLE
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The numbers n that solve sigma(n) = sigma(2n-1) are n = 1, 6, 348, 496, 1420, 1854, 4647, 5352, 6424, 13545, 21126,... The sequence selects the odd members.
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PROG
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(PARI) isok(n) = sigma(n) == sigma(2*n-1) && n % 2 == 1
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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