A064246 Numbers m such that N=(am+1)(bm+1)(cm+1) is a 3-Carmichael number (A087788), where a,b,c = 1,2,19.

7950, 8520, 9318, 25620, 29268, 29610, 32118, 44088, 48078, 67800, 70308, 72018, 83760, 95730, 133350, 138138, 174048, 175758, 176898, 186018, 188868, 225918, 244158, 256698, 265818, 280638, 289758

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@ 300000, PrimeQ[# + 1] && PrimeQ[2# + 1] && PrimeQ[19# + 1] && CarmichaelNbrQ[(# + 1)(2# + 1)(19# + 1)] &] (* Robert G. Wilson v, Aug 23 2012 *)

Extensions

Offset corrected by Amiram Eldar, Oct 16 2019