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A064597
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Nonunitary abundant numbers: the sum of the nonunitary divisors of n is larger than n; i.e. sigma(n) - usigma(n) > n.
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5
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36, 48, 72, 80, 96, 108, 120, 144, 160, 168, 180, 192, 200, 216, 224, 240, 252, 264, 280, 288, 300, 312, 320, 324, 336, 352, 360, 384, 392, 396, 400, 408, 416, 432, 448, 456, 468, 480, 504, 528, 540, 552, 560, 576, 588, 600, 612, 624, 640, 648, 672, 684
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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LINKS
| Harry J. Smith, Table of n, a(n) for n=1,...,1000
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EXAMPLE
| The sum of the nonunitary divisors of 36 is 2+3+6+12+18 = 41.
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MATHEMATICA
| nusigma[ n_ ] := DivisorSigma[ 1, n ]-Times@@(1+Power@@#&/@FactorInteger[ n ]); For[ n=1, True, n++, If[ nusigma[ n ]>n, Print[ n ] ] ]
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PROG
| (PARI) usigma(n)= { local(f, s=1); f=factor(n); for(i=1, matsize(f)[1], s*=1 + f[i, 1]^f[i, 2]); return(s) } { n=0; for (m=1, 10^9, if (sigma(m) - usigma(m) > m, write("b064597.txt", n++, " ", m); if (n==1000, break)) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 19 2009]
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CROSSREFS
| Cf. A048146, A064591, A064598, A063846.
Sequence in context: A167310 A083674 A160063 * A119850 A033701 A132956
Adjacent sequences: A064594 A064595 A064596 * A064598 A064599 A064600
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KEYWORD
| nonn,easy
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AUTHOR
| Dean Hickerson (dean.hickerson(AT)yahoo.com), Sep 25, 2001
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