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A083532
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First difference sequence of A007369. Differences between impossible values for sum of divisors of n.
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1
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3, 4, 1, 1, 5, 1, 2, 2, 1, 1, 2, 1, 1, 2, 4, 1, 1, 2, 4, 2, 2, 1, 1, 2, 1, 1, 1, 1, 2, 3, 1, 2, 3, 1, 1, 1, 2, 1, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 1, 1, 1, 1, 3, 2, 1, 2, 2, 1, 1, 2, 2, 1, 1, 2, 2, 2, 2, 1, 1, 1, 1, 3, 1, 2, 4, 1, 1, 3, 1, 1, 1, 2, 2, 1, 1, 2, 1, 1, 1, 1, 2, 2, 1, 1, 2, 2, 2, 2, 2, 1, 1, 2, 1, 2, 1
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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FORMULA
| a(n)=A007369[n+1]-A07369[n]
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EXAMPLE
| 29 and 33 are the 15th and 16th non-sense values for
sigma[x],since are no n of which they are sums of divisors,
while {30,31,32} equal sigma[x] e.g. for x=29,16,31 respectively,
thus 33-29=4=a(15)=A007369[16]-A007369[15].
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MATHEMATICA
| t0[x_] := Table[j, {j, 1, x}]; t=Table[DivisorSigma[1, w], {w, 1, 25000}]; u=Union[%]; c=Complement[t0[25000], u]; Delete[c-RotateRight[c], 1]
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CROSSREFS
| Cf. A002191, A007369, A083531-A083536.
Sequence in context: A046547 A016453 A158572 * A073366 A001086 A105283
Adjacent sequences: A083529 A083530 A083531 * A083533 A083534 A083535
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), May 20 2003
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