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A076495
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Smallest x such that Mod[sigma[x],x]=n, or 0 if no such x exists.
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2
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2, 20, 4, 9, 0, 25, 8, 10, 15, 14, 21, 24, 27, 22, 16, 26, 39, 208, 36, 34, 51, 38, 57, 112, 95, 46, 69, 48, 115, 841, 32, 58, 45, 62, 93, 660, 155, 1369, 162, 44, 63, 1681, 50, 82, 123, 52, 129, 60, 75, 94, 72, 352, 235, 90, 329, 84, 99, 68, 265, 96, 371, 118, 64, 76
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| The 0 entries are at present only conjectures.
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EXAMPLE
| n=1: solution=smallest prime. n=3: Mod[sigma[4],4]=Mod[7,4]=3=a(4), n=5: Very difficult case, no solution below 10^7.
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MATHEMATICA
| f[x_] := s=Mod[DivisorSigma[1, n], n]; t=Table[0, {256}]; Do[s=f[n]; If[s<257&&t[[s]]==0, t[[s]]=n], {n, 1, 10000000}]; t
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CROSSREFS
| Cf. A045768, A045769, A045770.
Sequence in context: A082259 A077339 A077341 * A058403 A083297 A012739
Adjacent sequences: A076492 A076493 A076494 * A076496 A076497 A076498
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Oct 21 2002
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EXTENSIONS
| The "more" keyword is because of the zero entries.
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