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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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified November 23 05:04 EST 2014. Contains 249839 sequences.