OFFSET
1,1
COMMENTS
The corresponding primes are 3, 7, 3, 31, 257, 13, 7, 5, 3, 73, ...
EXAMPLE
5 is in the sequence since lambda(5) = 4 and (2^4 - 1)/5 = 3 is prime.
MATHEMATICA
aQ[n_] := PrimeQ[(2^CarmichaelLambda[n]-1)/n]; a={}; Do[If[aQ[k], AppendTo[a, k]], {k, 1, 4000, 2}]; a
PROG
(PARI) isok(n) = (denominator(p=(2^lcm(znstar(n)[2])-1)/n)==1) && isprime(p); \\ Michel Marcus, Dec 29 2017
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Amiram Eldar, Dec 29 2017
STATUS
approved