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Search: id:A112646
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| A112646 |
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Special solutions to Abs[sigma[x+1]-sigma[x]]=2 where x+1 = 3^y. |
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+0
3
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| 8, 26, 2186, 1594322, 7509466514979724803946715958257546, 13915193059764305937984450503671774362956903094026
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OFFSET
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1,1
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COMMENT
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The relevant computed exponents providing -1+3^z solutions for A112645 are 2,3,7,13,71,103.
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MATHEMATICA
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ta={{0}}; Do[s=Abs[DivisorSigma[1, 3^n]-DivisorSigma[1, -1+3^n]]; If[Equal[s, 2], ta=Append[ta, n]; Print[ -1+3^n]], {n, 1, 100000000}]; ta=Delete[ta, 1]
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CROSSREFS
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Cf. A000203, A112645, A112647.
Adjacent sequences: A112643 A112644 A112645 this_sequence A112647 A112648 A112649
Sequence in context: A089064 A000810 A129663 this_sequence A084825 A119522 A070494
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KEYWORD
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more,nonn
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Sep 28 2005
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