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A167462 Primes p such that 2*p-5 is composite. 1
7, 13, 19, 31, 37, 41, 43, 61, 67, 73, 79, 83, 97, 103, 107, 109, 113, 127, 139, 151, 157, 163, 167, 173, 181, 191, 193, 199, 211, 223, 229, 239, 241, 251, 269, 271, 277, 283, 293, 307, 313, 317, 331, 337, 347, 349, 359, 367, 373, 379, 397, 409, 419, 421 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

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

MATHEMATICA

Select[Range[4, 3000], PrimeQ[#]&& ! PrimeQ[2 # - 5] &](* Vincenzo Librandi, Sep 15 2013 *)

Select[Prime[Range[100]], CompositeQ[2#-5]&] (* Harvey P. Dale, May 16 2016 *)

PROG

(MAGMA) [p: p in PrimesInInterval(4, 600)| not IsPrime(2*p-5)]; // Vincenzo Librandi, Sep 15 2013

CROSSREFS

Cf. A063909.

Sequence in context: A287217 A101324 A216830 * A088513 A004611 A129904

Adjacent sequences:  A167459 A167460 A167461 * A167463 A167464 A167465

KEYWORD

nonn,easy

AUTHOR

Vincenzo Librandi, Nov 04 2009

EXTENSIONS

Corrected (229 inserted) by R. J. Mathar, Nov 30 2009

Corrected (3 deleted, as 2*3-5 = 1 and 1 is not composite) by Harvey P. Dale, May 16 2016

STATUS

approved

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Last modified August 4 16:34 EDT 2020. Contains 336202 sequences. (Running on oeis4.)