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A081397
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Least x=a(n) such that GCD of sigma[x]=A000203(x) and phi[x]=A000010(x) equals n-th primorial=A002110[n].
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1
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OFFSET
| 1,1
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COMMENTS
| a(8) <= 1524139588224. [From Donovan Johnson (donovan.johnson(AT)yahoo.com), Dec 14 2009]
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FORMULA
| a[n]=Min{x; A081396[x]=A002110[n]}
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EXAMPLE
| n=284229: sigma[284229]=482790=2.3.5.7.11.19, phi[284229]=166320=2.2.2.3.3.3.3.5.7.11, common-factor-set={2,3,5,7,11}, GCD[sigma,phi]=2310.
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CROSSREFS
| Cf. A000203, A002110, A000010, A081383, A081396.
Sequence in context: A133028 A144985 A168590 * A092987 A088334 A050645
Adjacent sequences: A081394 A081395 A081396 * A081398 A081399 A081400
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KEYWORD
| nonn
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AUTHOR
| Labos E. (labos(AT)ana.sote.hu), Mar 28 2003
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EXTENSIONS
| a(6) corrected and a(7) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Dec 14 2009
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