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 A046025 Numbers n such that 6n+1, 12n+1 and 18n+1 are all primes. 13
 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. MATHEMATICA Select[Range[2000], And@@PrimeQ[{6, 12, 18}#+1]&] (* Harvey P. Dale, May 26 2014 *) CROSSREFS Cf. A033502, A002997. Sequence in context: A145000 A209182 A275407 * A198327 A009583 A033578 Adjacent sequences:  A046022 A046023 A046024 * A046026 A046027 A046028 KEYWORD nonn AUTHOR EXTENSIONS Better description from Robert G. Wilson v, Sep 27 2000 STATUS approved

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Last modified October 15 04:11 EDT 2018. Contains 316200 sequences. (Running on oeis4.)