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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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3
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OFFSET
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1,1
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COMMENTS
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The relevant computed exponents providing -1+3^z solutions for A112645 are 2, 3, 7, 13, 71, 103.
The next term, if it exists, is too large to include here. - N. J. A. Sloane, Jul 12 2009
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LINKS
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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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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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