

A036060


Number of 3component Carmichael numbers C = (6M + 1)(12M + 1)(18M + 1) < 10^n.


1



0, 1, 1, 2, 2, 3, 7, 10, 16, 25, 50, 86, 150, 256, 436, 783, 1435, 2631, 4765, 8766, 16320, 30601, 57719, 109504, 208822, 400643, 771735, 1494772, 2903761, 5658670, 11059937, 21696205, 42670184, 84144873, 66369603, 329733896, 655014986, 1303918824, 2601139051
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OFFSET

3,4


COMMENTS

Note that this is different from the count of 3Carmichael numbers, A132195. The numbers counted here are neither those listed in A087788 (3 arbitrary prime factors) nor those listed in A033502 (where 6m + 1, 12m + 1 and 18m + 1 are all prime).  M. F. Hasler, Apr 14 2015


REFERENCES

Posting by Harvey Dubner (harvey(AT)dubner.com) to Number Theory List (NMBRTHRY(AT)LISTSERV.NODAK.EDU), Nov 23 1998.


LINKS

Amiram Eldar, Table of n, a(n) for n = 3..42
H. Dubner, 3Component Carmichael Numberscorrection, Post to Number Theory List, Nov 23 1998.
Harvey Dubner, Carmichael Numbers of the form (6m+1)(12m+1)(18m+1), Journal of Integer Sequences, Vol. 5 (2002), Article 02.2.1.
Index entries for sequences related to Carmichael numbers.


CROSSREFS

Cf. A002997, A033502, A055553, A087788, A132195.
Sequence in context: A237988 A291102 A208494 * A227300 A065383 A087384
Adjacent sequences: A036057 A036058 A036059 * A036061 A036062 A036063


KEYWORD

nonn


AUTHOR

N. J. A. Sloane


EXTENSIONS

Terms updated (from Dubner's paper) by Amiram Eldar, Aug 11 2017


STATUS

approved



