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A119388
Numbers n such that n == -1 (mod phi(n-1)).
0
2, 3, 5, 7, 11, 31, 71, 511, 2591, 131071, 3359231, 167247871, 8589934591
OFFSET
1,1
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, Aug 08 2010]
PROG
(PARI) for(x=1, 70000000, if(((x)+1)%eulerphi((x)-1)==0, print((x))))
CROSSREFS
Cf. A067933.
Sequence in context: A028906 A118496 A085300 * A093487 A067933 A005234
KEYWORD
nonn
AUTHOR
Jorge Coveiro, Jul 25 2006
EXTENSIONS
a(13) from Donovan Johnson, Aug 08 2010
STATUS
approved