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A174612 Number of four-prime Carmichael numbers less than 10^n. 9
0, 0, 0, 0, 4, 19, 55, 144, 314, 619, 1179, 2102, 3639, 6042, 9938, 16202, 25758, 40685, 63343, 98253, 151566 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,5

LINKS

Table of n, a(n) for n=0..20.

R. G. E. Pinch, "The Carmichael numbers up to 10^21", Proceedings of Conference on Algorithmic Number Theory 2007

EXAMPLE

Example for n=5: the smallest Carmichael number with 4 prime factors is 41041 = 7 * 11 * 13 * 41.

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.

Sequence in context: A122684 A122681 A215862 * A020496 A108484 A283333

Adjacent sequences:  A174609 A174610 A174611 * A174613 A174614 A174615

KEYWORD

nonn,changed

AUTHOR

Michel Lagneau, Mar 23 2010

STATUS

approved

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Last modified August 20 22:45 EDT 2019. Contains 326155 sequences. (Running on oeis4.)