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 A101188 Values of n for which (7n+1)(8n+1)(11n+1) is a Carmichael number. 0
 18, 216, 24966, 228246, 299790, 403806, 413046, 446310, 514686, 760470, 948966, 1019190, 1087566, 1355526, 1374006, 1471950, 1582830, 1715886, 2159406, 2266590, 2334966, 2589990, 2833926, 3652590, 3661830, 3720966, 3874350 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS All values of n are even (since there are no even Carmichael numbers). Small values happen to be congruent to 18 modulo 66. This first fails for a(34)=5206142, which yields the Carmichael number 86921811895459937817345 = (3*5*29*83777)*41649137*57267563. Below this, only 4 values of n (18, 216, 299790 and 446310) correspond to Carmichael numbers with at least 4 prime factors. Other values of n must be of the form 1848k+942, with k given by A101186. LINKS G. P. Michon, Generic Carmichael Numbers. EXAMPLE a(1) = 18 corresponds to a 4-factor Carmichael number: 3664585 = 127 *(5*29) * 199. MATHEMATICA CarmichaelNbrQ[n_] := ! PrimeQ[n] && Mod[n, CarmichaelLambda[n]] == 1; Select[ Range[4000000], CarmichaelNbrQ[(7# + 1)(8# + 1)(11# + 1)] &] (* Robert G. Wilson v, Aug 24 2012 *) CROSSREFS Cf. A002997 (Carmichael numbers), A101186, A101187. Sequence in context: A009470 A111991 A081136 * A019757 A021503 A025470 Adjacent sequences:  A101185 A101186 A101187 * A101189 A101190 A101191 KEYWORD nonn AUTHOR Gerard P. Michon, Dec 08 2004 STATUS approved

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Last modified October 15 19:25 EDT 2019. Contains 328037 sequences. (Running on oeis4.)