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A119388
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Numbers n such that n == -1 (mod phi(n-1)).
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0
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2, 3, 5, 7, 11, 31, 71, 511, 2591, 131071, 3359231, 167247871, 8589934591
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| This sequence has the terms from A067933 (all primes), plus 511 and 3359231 that are not primes.
Checked up to x<70000000
a(14) > 10^11. [From Donovan Johnson (donovan.johnson(AT)yahoo.com), Aug 08 2010]
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PROG
| (PARI) for(x=1, 70000000, if(((x)+1)%eulerphi((x)-1)==0, print((x))))
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CROSSREFS
| Cf. A067933.
Sequence in context: A028906 A118496 A085300 * A093487 A067933 A005234
Adjacent sequences: A119385 A119386 A119387 * A119389 A119390 A119391
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KEYWORD
| nonn
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AUTHOR
| Jorge Coveiro (jorgecoveiro(AT)yahoo.com), Jul 25 2006
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EXTENSIONS
| a(13) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Aug 08 2010
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