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A172015 Numbers of the form 6*k-+1 such that 6*k-1=prime and 6*k+1=nonprime. 2
23, 25, 47, 49, 53, 55, 83, 85, 89, 91, 113, 115, 131, 133, 167, 169, 173, 175, 233, 235, 251, 253, 257, 259, 263, 265, 293, 295, 317, 319, 353, 355, 359, 361, 383, 385, 389, 391, 401, 403, 443, 445, 449, 451, 467, 469, 479, 481, 491, 493, 503, 505, 509, 511 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..54.

MATHEMATICA

Select[Table[{6k-1, 6k+1}, {k, 1, 100}], PrimeQ[ #[[1]] ] && !PrimeQ[ #[[2]] ]&] // Flatten (* Jean-Fran├žois Alcover, Nov 24 2016 *)

CROSSREFS

A171688 U A171697 U A172015 U A172016 = A007310.

Sequence in context: A093805 A033629 A090311 * A112073 A050864 A111452

Adjacent sequences:  A172012 A172013 A172014 * A172016 A172017 A172018

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Jan 22 2010

EXTENSIONS

Entries checked by R. J. Mathar, Apr 14 2010

STATUS

approved

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Last modified January 28 12:46 EST 2022. Contains 350656 sequences. (Running on oeis4.)