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A259826 Numbers n such that n is a multiple of 6 and both n-1 and n+1 are composite. 2
120, 144, 186, 204, 216, 246, 288, 300, 324, 342, 414, 426, 474, 516, 528, 534, 552, 582, 624, 636, 666, 696, 714, 780, 792, 804, 816, 834, 846, 870, 894, 900, 924, 960, 1002, 1026, 1044, 1056, 1074, 1080, 1134, 1140, 1146, 1158, 1176, 1206, 1242, 1254, 1266, 1272, 1314, 1332, 1338, 1344, 1350 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Harvey P. Dale, Table of n, a(n) for n = 1..2500

EXAMPLE

For n=120, 120 is a multiple of 6, and both 119 and 121 are composite.

MATHEMATICA

Select[6*Range[500], AllTrue[# + {1, -1}, CompositeQ] &] (* Harvey P. Dale, May 21 2017 *)

PROG

(PARI) select(x->!isprime(x-1)&&!isprime(x+1), vector(10^3, j, 6*j) ) \\ Joerg Arndt, Jul 06 2015

(MAGMA) [n: n in [6..2000 by 6] | not IsPrime(n-1) and not IsPrime(n+1)]; // Vincenzo Librandi, Jul 08 2015

CROSSREFS

Intersection of A008588 and A099047. - Michel Marcus, Jul 06 2015

Cf. A060461.

Sequence in context: A074302 A095631 A248662 * A192277 A034291 A039602

Adjacent sequences:  A259823 A259824 A259825 * A259827 A259828 A259829

KEYWORD

nonn

AUTHOR

Antonio Gimenez, Jul 05 2015

STATUS

approved

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Last modified November 19 19:09 EST 2019. Contains 329323 sequences. (Running on oeis4.)