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A083531
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First difference sequence of A002191. Differences between possible values for sum of divisors of n.
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4
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2, 1, 2, 1, 1, 4, 1, 1, 1, 3, 2, 4, 4, 2, 1, 1, 4, 2, 1, 1, 2, 2, 4, 6, 2, 1, 3, 2, 1, 5, 4, 2, 4, 2, 4, 6, 1, 2, 3, 2, 4, 2, 4, 2, 2, 2, 6, 1, 3, 2, 1, 1, 4, 1, 5, 2, 4, 6, 2, 4, 2, 2, 2, 2, 4, 3, 3, 2, 4, 2, 1, 3, 6, 2, 1, 3, 2, 4, 6, 2, 4, 1, 5, 2, 4, 2, 4, 6, 2, 6, 4, 3, 1, 2, 2, 4, 2, 4, 2, 6, 2, 2, 2, 4, 6
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OFFSET
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1,1
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LINKS
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Table of n, a(n) for n=1..105.
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EXAMPLE
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8 and 12 are the 6th and 7th possible values for
sigma[x],since are sum of divisors of x=7 and x=11
respectively, while 9,10,11 are impossible ones
so 12-8=4=a(6)=A002191[7]-A002191[6].
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MATHEMATICA
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t=Table[DivisorSigma[1, w], {w, 1, 25000}]; u=Union[%]; Delete[u-RotateRight[u], 1]
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CROSSREFS
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Cf. A002191, A007609, A007369, A083532-A083536.
Sequence in context: A134303 A078997 A024680 * A003417 A158986 A079900
Adjacent sequences: A083528 A083529 A083530 * A083532 A083533 A083534
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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), May 20 2003
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STATUS
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approved
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