A064241 Values of m such that N=(am+1)(bm+1)(cm+1) is a 3-Carmichael number (A087788), where a,b,c = 1,2,9.

30, 228, 498, 1398, 1758, 2028, 2280, 3180, 4800, 5430, 6150, 6420, 6708, 7950, 8688, 9930, 11838, 13728, 16518, 16878, 17490, 19488, 26040, 28200, 30108, 30468, 33528, 33870, 34140, 34500, 35490, 35670, 38298, 38820, 39900, 40350

Offset: 1

Author

N. J. A. Sloane, Sep 23 2001

Keywords

• nonn

Comments

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

References

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

Links

• Amiram Eldar, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A087788.

Programs

Mathematica

CarmichaelNbrQ[n_] := ! PrimeQ@ n && Mod[n, CarmichaelLambda@ n] == 1; Select[ Range@ 42000, PrimeQ[# + 1] && PrimeQ[2# + 1] && PrimeQ[9# + 1] && CarmichaelNbrQ[(# + 1)(2# + 1)(9# + 1)] &] (* Robert G. Wilson v, Aug 23 2012 *)

Extensions

Offset corrected by Amiram Eldar, Oct 16 2019