

A135437


Primes with a twin Carmichael number: primes p such that p2 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
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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



