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A099634
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a[n]=GCD[P+p,P*p] where P is the largest and p the smallest prime factor of n.
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3
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4, 3, 4, 5, 1, 7, 4, 3, 1, 11, 1, 13, 1, 1, 4, 17, 1, 19, 1, 1, 1, 23, 1, 5, 1, 3, 1, 29, 1, 31, 4, 1, 1, 1, 1, 37, 1, 1, 1, 41, 1, 43, 1, 1, 1, 47, 1, 7, 1, 1, 1, 53, 1, 1, 1, 1, 1, 59, 1, 61, 1, 1, 4, 1, 1, 67, 1, 1, 1, 71, 1, 73, 1, 1, 1, 1, 1, 79, 1, 3, 1, 83, 1, 1, 1, 1, 1, 89, 1, 1, 1, 1, 1, 1, 1, 97
(list; graph; refs; listen; history; internal format)
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OFFSET
| 2,1
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EXAMPLE
| If n is prime q>2, then a[n]=GCD[q^2,2q]=q.
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MATHEMATICA
| PrimeFactors[n_Integer] := Flatten[ Table[ # [[1]], {1}] & /@ FactorInteger[n]]; f[n_] := Block[{pf = PrimeFactors[n]}, GCD[pf[[1]] + pf[[ -1]], pf[[1]]*pf[[ -1]] ]]; Table[ f[n], {n, 2, 97}] (from Robert G. Wilson v Nov 04 2004)
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CROSSREFS
| Sequence in context: A204671 A204816 A204818 * A203144 A109382 A090369
Adjacent sequences: A099631 A099632 A099633 * A099635 A099636 A099637
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Oct 28 2004
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