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Search: id:A156903
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| A156903 |
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Numbers whose abundance is odd. |
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+0
3
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| 18, 36, 72, 100, 144, 162, 196, 200, 288, 324, 392, 400, 450, 576, 648, 784, 800, 882, 900, 968, 1152, 1296, 1352, 1458, 1568, 1600, 1764, 1800, 1936, 2178, 2304, 2450, 2500, 2592, 2704, 2916, 3042, 3136, 3200, 3528, 3600, 3872, 4050, 4356, 4608, 4624
(list; graph; listen)
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OFFSET
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1,1
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LINKS
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Eric Weisstein's World of Mathematics, Abundant Number
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EXAMPLE
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18 is in the sequence because its divisors are {1,2,3,6,9,18} which sum to 39; so its abundancy is 3.
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MATHEMATICA
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f[n_] := DivisorSigma[1, n] - 2 n; Select[ Range@ 10000, f@# > 0 && Mod[f@#, 2] == 1 &]
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CROSSREFS
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Cf. A005101. A proper subset of A083211.
Sequence in context: A087967 A070224 A083211 this_sequence A023149 A115550 A061713
Adjacent sequences: A156900 A156901 A156902 this_sequence A156904 A156905 A156906
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KEYWORD
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nonn
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AUTHOR
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Robert G. Wilson v (rgwv(AT)rgwv.com), Feb 17 2009
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