

A046025


Numbers n such that 6n+1, 12n+1 and 18n+1 are all primes.


9



1, 6, 35, 45, 51, 55, 56, 100, 121, 195, 206, 216, 255, 276, 370, 380, 426, 506, 510, 511, 710, 741, 800, 825, 871, 930, 975, 1025, 1060, 1115, 1140, 1161, 1270, 1280, 1281, 1311, 1336, 1361, 1365, 1381, 1420, 1421, 1441, 1490, 1515, 1696, 1805, 1875, 1885
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OFFSET

1,2


COMMENTS

n is a Carmichael number generator giving C(n) = (6n+1)(12n+1)(18n+1).


REFERENCES

Ivan Niven, Herbert S. Zuckerman and Hugh L. Montgomery, An Introduction to the Theory Of Numbers, Fifth Edition, Wiley NY 1991, page 83, problem #20.
R. K. Guy, Unsolved Problems in Number Theory, A13.


LINKS

Donovan Johnson, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Carmichael Number.
Index entries for sequences related to Carmichael numbers.


MATHEMATICA

Select[Range[2000], And@@PrimeQ[{6, 12, 18}#+1]&] (* Harvey P. Dale, May 26 2014 *)


CROSSREFS

Cf. A033502, A002997.
Sequence in context: A230941 A145000 A209182 * A198327 A009583 A033578
Adjacent sequences: A046022 A046023 A046024 * A046026 A046027 A046028


KEYWORD

nonn


AUTHOR

Eric W. Weisstein


EXTENSIONS

Better description from Robert G. Wilson v, Sep 27 2000


STATUS

approved



