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A143772
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If m is the n-th composite, then a(n) = GCD(k +m/k), where k is over all divisors of m.
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1
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1, 1, 3, 2, 1, 1, 3, 8, 1, 1, 3, 2, 1, 1, 2, 3, 4, 1, 1, 3, 2, 1, 12, 1, 3, 8, 1, 1, 3, 2, 1, 1, 2, 3, 4, 1, 1, 8, 3, 2, 1, 1, 3, 8, 1, 6, 1, 3, 2, 1, 1, 3, 4, 1, 6, 1, 3, 2, 1, 1, 2, 3, 8, 1, 1, 4, 3, 2, 1, 24, 1, 3, 4, 1, 1, 3, 2, 1, 1, 3, 8, 1, 1, 4, 3, 2, 1, 24, 1, 2, 3, 4, 1, 6, 1, 3, 2, 1, 1, 2, 3, 8, 1, 1, 3
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,3
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COMMENTS
| Conjecture: All even numbers are members and the only odd numbers which are members are 1 & 3. [From Robert G. Wilson v (rgwv(AT)rgwv.com), Sep 08 2008]
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EXAMPLE
| For n=11, 20 is the 11th composite. So we have: a(11) = GCD(1+20,2+10,4+5,5+4,10+2,20+1) = 3.
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MATHEMATICA
| Composite[n_Integer] := FixedPoint[n + PrimePi@# + 1 &, n + PrimePi@n + 1]; f[n_] := Block[{m = Composite@n}, Last@ FoldList[ GCD, m!, # + m/# & /@ Divisors@m]]; Array[f, 105] [From Robert G. Wilson v (rgwv(AT)rgwv.com), Sep 08 2008]
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CROSSREFS
| Cf. A143771.
Sequence in context: A134520 A188316 A197027 * A053989 A097794 A137683
Adjacent sequences: A143769 A143770 A143771 * A143773 A143774 A143775
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KEYWORD
| nonn
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AUTHOR
| Leroy Quet Aug 31 2008
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EXTENSIONS
| More terms from Robert G. Wilson v (rgwv(AT)rgwv.com), Sep 08 2008
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