A064250 Values of m such that N=(am+1)(bm+1)(cm+1) is a 3-Carmichael number (A087788), where a,b,c = 1,2,27.

606, 2280, 3036, 3738, 7950, 15348, 16266, 20640, 21558, 23826, 26040, 27066, 28686, 30576, 31386, 31656, 32358, 33870, 36570, 47856, 49476, 53148, 57036, 64920, 65028, 70536, 72480, 80526, 85818, 86466, 92568, 94350, 96996, 102828

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@ 105000, PrimeQ[# + 1] && PrimeQ[2# + 1] && PrimeQ[27# + 1] && CarmichaelNbrQ[(# + 1)(2# + 1)(27# + 1)] &] (* Robert G. Wilson v, Aug 23 2012 *)

Extensions

Offset corrected by Amiram Eldar, Oct 17 2019