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A172147 Numbers n such that 42n - 5 and 42n + 5 are prime. 3
1, 2, 4, 9, 11, 12, 17, 18, 21, 22, 26, 28, 29, 31, 34, 37, 43, 49, 56, 57, 64, 66, 68, 79, 86, 88, 104, 106, 114, 117, 119, 121, 133, 138, 144, 148, 152, 166, 171, 172, 182, 183, 192, 193, 199, 204, 207, 208, 213, 218, 224, 229, 232, 233, 242, 244, 249, 257, 264, 268, 276 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Ivan Neretin, Table of n, a(n) for n = 1..10000

EXAMPLE

a(1)=1 because 42*1 - 5 = 37 and 42*1 + 5 = 47 are both prime.

MATHEMATICA

Select[Range[280], PrimeQ[42 # - 5] && PrimeQ[42 # + 5] &] (* Ivan Neretin, Jan 24 2017 *)

CROSSREFS

Sequence in context: A005733 A096692 A203847 * A266726 A030194 A190494

Adjacent sequences:  A172144 A172145 A172146 * A172148 A172149 A172150

KEYWORD

nonn,easy

AUTHOR

Juri-Stepan Gerasimov, Jan 26 2010

EXTENSIONS

Corrected by Charles R Greathouse IV, Mar 19 2010

STATUS

approved

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Last modified December 8 18:37 EST 2019. Contains 329865 sequences. (Running on oeis4.)