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%I #22 Jan 04 2022 11:54:09
%S 1,6,35,45,51,55,56,100,121,195,206,216,255,276,370,380,426,506,510,
%T 511,710,741,800,825,871,930,975,1025,1060,1115,1140,1161,1270,1280,
%U 1281,1311,1336,1361,1365,1381,1420,1421,1441,1490,1515,1696,1805,1875,1885
%N Numbers n such that 6n+1, 12n+1 and 18n+1 are all primes.
%C Main entry for this sequence is A033502.
%C n is a Carmichael number generator giving C(n) = (6n+1)(12n+1)(18n+1).
%D 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.
%D R. K. Guy, Unsolved Problems in Number Theory, A13.
%H Donovan Johnson, <a href="/A046025/b046025.txt">Table of n, a(n) for n = 1..10000</a>
%H Eric Weisstein's World of Mathematics, <a href="http://mathworld.wolfram.com/CarmichaelNumber.html">Carmichael Number.</a>
%H <a href="/index/Ca#Carmichael">Index entries for sequences related to Carmichael numbers.</a>
%t Select[Range[2000],And@@PrimeQ[{6,12,18}#+1]&] (* _Harvey P. Dale_, May 26 2014 *)
%o (PARI) is(n)=isprime(6*n+1) && isprime(12*n+1) && isprime(18*n+1) \\ _Charles R Greathouse IV_, Jan 04 2022
%Y Cf. A033502, A002997.
%K nonn
%O 1,2
%A _Eric W. Weisstein_
%E Better description from _Robert G. Wilson v_, Sep 27 2000
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