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A165637 Primes p such that (p^2-3)/2 is not a prime number. 1
2, 17, 43, 53, 59, 61, 71, 83, 89, 107, 113, 127, 131, 137, 139, 149, 163, 167, 173, 179, 181, 191, 193, 199, 223, 229, 241, 251, 269, 271, 277, 281, 283, 311, 313, 317, 347, 373, 379, 383, 401, 419, 421, 431, 433, 439, 457, 461, 467, 479, 499, 503, 523, 541, 557, 563 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..1000

FORMULA

A000040 \ A110589. - R. J. Mathar, Sep 26 2009

EXAMPLE

For p=17=a(2), (17^2-3)/2=143 is not a prime. For p=43=a(3), (43^2-3)/2=923 is not a prime.

MATHEMATICA

Select[Prime[Range[200]], !PrimeQ[(#^2 - 3) / 2]&] (* Harvey P. Dale, Dec 09 2011 *)

PROG

(MAGMA) [p: p in PrimesUpTo(600)| not IsPrime((p^2-3) div 2)]; // Vincenzo Librandi, Sep 12 2013

CROSSREFS

Sequence in context: A256145 A096172 A120745 * A100271 A046973 A226488

Adjacent sequences:  A165634 A165635 A165636 * A165638 A165639 A165640

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Sep 23 2009

EXTENSIONS

Extended by R. J. Mathar, Sep 26 2009

STATUS

approved

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Last modified August 20 01:14 EDT 2019. Contains 326136 sequences. (Running on oeis4.)