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A231573 Composite numbers n such that lambda(n) divides 6n-6, where lambda is the Carmichael lambda function (A002322). 4
4, 6, 8, 9, 12, 14, 15, 18, 21, 24, 28, 35, 36, 39, 42, 45, 56, 63, 65, 66, 72, 76, 84, 91, 105, 117, 126, 133, 153, 168, 186, 195, 231, 247, 252, 259, 273, 276, 315, 341, 344, 396, 435, 455, 481, 504, 532, 561, 585, 616, 645, 651, 671, 703, 804, 819, 861 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Contains the Carmichael numbers, A231569 and A231570.

Conjecture: the relative asymptotic density of Carmichael numbers in this sequence exists, is positive and smaller than 1.

LINKS

Charles R Greathouse IV, Table of n, a(n) for n = 1..10000

J. M. Grau and Antonio Oller-Marcén, Generalizing Giuga's conjecture, arXiv:1103.3483 [math.NT], 2011.

MATHEMATICA

Select [1 + Range[100000], ! PrimeQ[#] && IntegerQ[6 (# -1)/ CarmichaelLambda[#]] &]

PROG

(PARI) is(n)=!isprime(n) && (6*n-6)%lcm(znstar(n)[2])==0 && n>1 \\ Charles R Greathouse IV, Nov 13 2013

CROSSREFS

Cf. A231569-A231575, A002322.

Sequence in context: A259315 A211771 A211772 * A327204 A047409 A161576

Adjacent sequences:  A231570 A231571 A231572 * A231574 A231575 A231576

KEYWORD

nonn

AUTHOR

José María Grau Ribas, Nov 11 2013

STATUS

approved

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Last modified April 6 10:28 EDT 2020. Contains 333273 sequences. (Running on oeis4.)