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A231569
Composite numbers n such that lambda(n) divides 2n-2, where lambda is the Carmichael lambda function (A002322).
6
4, 6, 8, 12, 15, 24, 28, 66, 91, 276, 435, 532, 561, 616, 703, 946, 1105, 1128, 1288, 1729, 1891, 2465, 2701, 2821, 2926, 3367, 5551, 6601, 8646, 8695, 8911, 10585, 11305, 11476, 12403, 13981, 15051, 15841, 16471, 18721, 19096, 23001, 26335, 29341, 30889
OFFSET
1,1
COMMENTS
Contains the Carmichael numbers (A002997).
Conjecture: the relative asymptotic density of the Carmichael numbers in this sequence exists, is positive and smaller than 1.
LINKS
J. M. Grau and Antonio Oller-Marcén, Generalizing Giuga's conjecture, arXiv:1103.3483 [math.NT], 2011.
MATHEMATICA
Select [1 + Range[100000], ! PrimeQ[#] && IntegerQ[2 (# -1)/ CarmichaelLambda[#]] &]
PROG
(PARI) is(n)=!isprime(n) && (2*n-2)%lcm(znstar(n)[2])==0 && n>1 \\ Charles R Greathouse IV, Nov 13 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
STATUS
approved