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A231572
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Composite numbers n such that lambda(n) divides 5n-5, where lambda is the Carmichael lambda function (A002322).
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4
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25, 33, 165, 217, 325, 385, 561, 793, 825, 1025, 1045, 1065, 1105, 1353, 1525, 1705, 1729, 2465, 2665, 2821, 3565, 4123, 4681, 5005, 5185, 5425, 6601, 6697, 8029, 8569, 8911, 9073, 10585, 11005, 12025, 12505, 12801, 13237, 13741, 14707, 14725, 14905, 15457
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OFFSET
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1,1
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COMMENTS
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Contains the Carmichael numbers (A002997).
Conjecture: the relative asymptotic density of the Carmichael numbers in this sequence exists, is positive and smaller than 1.
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LINKS
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Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
J. M. Grau and Antonio Oller-Marcén, Generalizing Giuga's conjecture, arXiv:1103.3483 [math.NT], 2011.
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MATHEMATICA
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Select [1 + Range[100000], ! PrimeQ[#] && IntegerQ[5 (# -1)/ CarmichaelLambda[#]] &]
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PROG
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(PARI) is(n)=!isprime(n) && (5*n-5)%lcm(znstar(n)[2])==0 && n>1 \\ Charles R Greathouse IV, Nov 13 2013
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CROSSREFS
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Cf. A231569-A231575, A002322.
Sequence in context: A068411 A020160 A075452 * A020258 A227516 A281369
Adjacent sequences: A231569 A231570 A231571 * A231573 A231574 A231575
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KEYWORD
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nonn
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AUTHOR
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José María Grau Ribas, Nov 11 2013
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STATUS
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approved
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