A174612 Number of four-prime Carmichael numbers less than 10^n.

0, 0, 0, 0, 0, 4, 19, 55, 144, 314, 619, 1179, 2102, 3639, 6042, 9938, 16202, 25758, 40685, 63343, 98253, 151566, 232742

Offset: 0

Author

Michel Lagneau, Mar 23 2010

Keywords

• nonn
• more

Examples

			For n=5, the smallest Carmichael number with 4 prime factors is 41041 = 7*11*13*41.
		

References

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

Links

• Claude Goutier, Text file readme.text summarizing enumeration of Carmichael numbers up to 10^22.
• Claude Goutier, Text file readme.text summarizing enumeration of Carmichael numbers up to 10^22. [Local copy, with permission]
• R. G. E. Pinch, The Carmichael numbers up to 10^21, Proceedings of Conference on Algorithmic Number Theory 2007.

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.

Extensions

a(0) inserted and a(22) from Claude Goutier added by Amiram Eldar, Apr 19 2024