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A161868 Primes p such that both p+2 and p-2 are products of 3 distinct primes. 1
1237, 1493, 1549, 1597, 2137, 2753, 2767, 2917, 3533, 3617, 4013, 4253, 4919, 5557, 5683, 5693, 5783, 6151, 6353, 6367, 6917, 6967, 6983, 7057, 7187, 7537, 7687, 7703, 7883, 8101, 8167, 8243, 8447, 8699, 8731, 8963, 9697, 9739, 9787, 9833, 9887, 10151 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Chai Wah Wu, Table of n, a(n) for n = 1..10000

EXAMPLE

1237-2=5*13*19. 1237+2=3*7*59. 1493-2=3*7*71. 1493+2=5*13*23.

MATHEMATICA

fQ[n_]:=Last/@FactorInteger[n]=={1, 1, 1}; q=2; lst={}; Do[p=Prime[n]; If[fQ[p-q]&&fQ[p+q], AppendTo[lst, p]], {n, 7!}]; lst

Select[Prime[Range[1250]], FactorInteger[#+2][[All, 2]]== FactorInteger[ #-2] [[All, 2]]=={1, 1, 1}&] (* Harvey P. Dale, Aug 03 2016 *)

CROSSREFS

Cf. A007304. [R. J. Mathar, Jun 23 2009]

Sequence in context: A210515 A122043 A179913 * A145047 A236974 A237552

Adjacent sequences:  A161865 A161866 A161867 * A161869 A161870 A161871

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, Jun 20 2009

EXTENSIONS

Definition rephrased by R. J. Mathar, Jun 23 2009

STATUS

approved

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Last modified May 26 22:57 EDT 2019. Contains 323597 sequences. (Running on oeis4.)