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A055720
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Numbers k such that d(k)+1 | k.
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1
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3, 4, 10, 15, 28, 35, 54, 55, 63, 64, 65, 85, 95, 98, 100, 115, 125, 135, 144, 145, 147, 155, 156, 175, 176, 185, 189, 205, 215, 234, 235, 245, 260, 265, 295, 297, 305, 335, 336, 351, 355, 364, 365, 395, 400, 408, 415, 416, 445, 459, 485
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OFFSET
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1,1
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COMMENTS
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Integers divisible by 1 more than the number of their divisors. The only prime is 3.
These numbers cannot be very orderly numbers (A167409). - T. D. Noe, Nov 13 2009
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LINKS
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MATHEMATICA
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Select[Range[1000], Mod[ #, 1 + DivisorSigma[0, # ]] == 0 &]
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PROG
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(PARI) isok(k) = Mod(k, numdiv(k)+1) == 0; \\ Michel Marcus, Mar 12 2020
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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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