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A046025
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Numbers n such that 6n+1, 12n+1 and 18n+1 are all primes.
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9
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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
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1,2
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COMMENTS
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n is a Carmichael number generator giving C(n) = (6n+1)(12n+1)(18n+1).
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REFERENCES
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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.
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LINKS
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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.
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MATHEMATICA
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Select[Range[2000], PrimeQ[6# + 1] && PrimeQ[12# + 1] && PrimeQ[18# + 1] &]
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CROSSREFS
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Cf. A033502, A002997.
Sequence in context: A003423 A145000 A209182 * A198327 A009583 A033578
Adjacent sequences: A046022 A046023 A046024 * A046026 A046027 A046028
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KEYWORD
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nonn
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AUTHOR
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Eric W. Weisstein
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EXTENSIONS
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Better description from Robert G. Wilson v, Sep 27 2000
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STATUS
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approved
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