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A119388 Numbers n such that n == -1 (mod phi(n-1)). 0

%I

%S 2,3,5,7,11,31,71,511,2591,131071,3359231,167247871,8589934591

%N Numbers n such that n == -1 (mod phi(n-1)).

%C This sequence has the terms from A067933 (all primes), plus 511 and 3359231 that are not primes.

%C Checked up to x<70000000

%C a(14) > 10^11. [From _Donovan Johnson_, Aug 08 2010]

%o (PARI) for(x=1,70000000,if(((x)+1)%eulerphi((x)-1)==0,print((x))))

%Y Cf. A067933.

%K nonn

%O 1,1

%A _Jorge Coveiro_, Jul 25 2006

%E a(13) from _Donovan Johnson_, Aug 08 2010

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Last modified September 27 20:47 EDT 2021. Contains 347694 sequences. (Running on oeis4.)