A132195 Number of three-prime Carmichael numbers less than 10^n.

1, 7, 12, 23, 47, 84, 172, 335, 590, 1000, 1858, 3284, 6083, 10816, 19539, 35586, 65309, 120625, 224763, 420658, 790885, 1494738

Offset: 3

Author

Jonathan Vos Post, Nov 19 2007

Keywords

• nonn
• more

Comments

a(n) = C_3(n) in Table 1, p. 34 of Chick (2007-2008) = card{c such that c is in A002997 INTERSECTION A014612 and c <= 10^n}.

References

• Paulo Ribenboim, The Little Book of Bigger Primes, Springer-Verlag NY 2004. See p. 220.

Links

• J. M. Chick, Carmichael number variable relations: three-prime Carmichael numbers up to 10^24, arXiv:0711.2915 [math.NT], 2007-2008, Table 1, p. 34.
• Andrew Granville and Carl Pomerance, Two contradictory conjectures concerning Carmichael numbers, Mathematics of Computation, Vol. 71, No. 238 (2002), pp. 883-908.

Crossrefs

For k-prime Carmichael numbers up to 10^n for k = 3,4,...,11, see A132195, A174612, A174613, A174614, A174615, A174616, A174617, A299710, A299711.

Cf. A002997, A006931, A055553.