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 A135437 Primes with a twin Carmichael number: primes p such that p-2 or p+2 are Carmichael numbers. 2
 563, 1103, 2467, 2819, 6599, 29339, 41039, 52631, 62743, 172079, 188459, 278543, 340559, 488879, 656599, 656603, 670031, 1033667, 1909003, 2100899, 3146219, 5048999, 6049679, 8719307, 10024559, 10402559, 10877579, 11119103, 12261059, 14913989, 15247619 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..1878 from Pierre CAMI) EXAMPLE 563 is in the sequence since it is a prime number, and 563 - 2 = 561 is a Carmichael number. 1103 is in the sequence since it is a prime number, and 1103 + 2 = 1105 is a Carmichael number. MATHEMATICA s = {}; carmichaelQ[n_] := CompositeQ[n] && Divisible[n - 1, CarmichaelLambda[n]]; Do[If[carmichaelQ[n], If[PrimeQ[n - 2], AppendTo[s, n - 2]]; If[PrimeQ[n + 2], AppendTo[s, n + 2]]], {n, 10^6}]; s (* Amiram Eldar, Jul 07 2019 *) CROSSREFS Cf. A002997, A287591. Sequence in context: A250976 A209907 A232679 * A142759 A187849 A237029 Adjacent sequences:  A135434 A135435 A135436 * A135438 A135439 A135440 KEYWORD nonn AUTHOR Pierre CAMI, Dec 14 2007, corrected Jun 22 2008; Sep 17 2008 STATUS approved

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Last modified September 22 17:16 EDT 2020. Contains 337291 sequences. (Running on oeis4.)