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Search: id:A070015
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| A070015 |
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Least m such that sum of aliquot parts of m [A001065(m)] equals n or 0 if no such number exists. |
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+0
4
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| 2, 0, 4, 9, 0, 6, 8, 10, 15, 14, 21, 121, 27, 22, 16, 12, 39, 289, 65, 34, 18, 20, 57, 529, 95, 46, 69, 28, 115, 841, 32, 58, 45, 62, 93, 24, 155, 1369, 217, 44, 63, 30, 50, 82, 123, 52, 129, 2209, 75, 40, 141, 0, 235, 42, 36, 106, 99, 68, 265, 3481, 371, 118, 64, 56
(list; graph; listen)
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OFFSET
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1,1
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LINKS
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Richard J Mathar, Table of n, a(n) for n = 1..9884
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FORMULA
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a(n)=Min{x; A001065(x)=n} or a(n)=0 if n is untouchable number (i.e. if from A005114)
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EXAMPLE
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n=128: a(n)=16129, divisors={1,127,16129}, 1+127=sigma[n]-n=128 and 16129 is the smallest.
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MATHEMATICA
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f[x_] := DivisorSigma[1, x]-x; t=Table[0, {128}]; Do[c=f[n]; If[c<129&&t[[c]]==0, t[[c]]=n], {n, 1, 1000000}]; t
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CROSSREFS
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Cf. A000203, A001065, A048050, A051444, A007369, A070016, A005114, A048995.
Sequence in context: A115780 A101189 A001443 this_sequence A021492 A077119 A002938
Adjacent sequences: A070012 A070013 A070014 this_sequence A070016 A070017 A070018
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KEYWORD
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nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Apr 12 2002
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