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A064238 Values of m such that N=(am+1)(bm+1)(cm+1) is a Carmichael number, where a,b,c = 1,2,3. 14
6, 36, 210, 270, 306, 330, 336, 600, 726, 1170, 1236, 1296, 1530, 1656, 2220, 2280, 2556, 3036, 3060, 3066, 4260, 4446, 4800, 4950, 5226, 5580, 5850, 6150, 6360, 6690, 6840, 6966, 7620, 7680, 7686, 7866, 8016, 8166, 8190, 8286, 8520 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

am+1, bm+1, cm+1 are primes and am | (N-1), bm | (N-1), cm |(N-1).

All m's are multiples of 6 and m, 2m and 3m divide m(2m+1)(3m+1)-1 automatically.

REFERENCES

Harvey Dubner (harvey(AT)dubner.com), personal communication, Jun 27 2001.

LINKS

Table of n, a(n) for n=0..40.

FORMULA

a(n) = 6 * A046025(n+1).

MATHEMATICA

CarmichaelNbrQ[n_] := ! PrimeQ@ n && Mod[n, CarmichaelLambda[n]] == 1; Select[ Range@ 9000, PrimeQ[# + 1] && PrimeQ[2# + 1] && PrimeQ[3# + 1] && CarmichaelNbrQ[(# + 1)(2 # + 1)(3 # + 1)] &] (* Robert G. Wilson v, Aug 23 2012 *)

CROSSREFS

Cf. A046025.

Sequence in context: A225685 A006812 A111989 * A014336 A268941 A269637

Adjacent sequences:  A064235 A064236 A064237 * A064239 A064240 A064241

KEYWORD

nonn

AUTHOR

N. J. A. Sloane, Sep 23 2001

STATUS

approved

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Last modified November 14 06:14 EST 2018. Contains 317162 sequences. (Running on oeis4.)