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A283191
Prime numbers p > 2 such that (2^p - 5)/3 is prime.
0
7, 13, 19, 31, 373, 811, 1117, 5059, 12601
OFFSET
1,1
COMMENTS
Let W = (2^p - 5)/3 and s = (W+1)/(2*p), then 5^s == 2 (mod W) for terms 1..9.
Subsequence of 7, 13, 19, 31, 51, 55, 85, 111, 319, 373,.. which are numbers m such that (2^m-5)/3 is prime. - R. J. Mathar, Mar 05 2017
MATHEMATICA
Select[Prime@ Range[2, 1000], PrimeQ[(2^# - 5)/3] &] (* Michael De Vlieger, Mar 03 2017 *)
PROG
(PARI)
forprime(p=3, 30000, W= (2^p-5)/3; if(ispseudoprime(W), print1(p, ", ")))
CROSSREFS
Cf. A000978.
Sequence in context: A373584 A122482 A265629 * A048375 A198035 A208720
KEYWORD
nonn,more
AUTHOR
Dmitry Ezhov, Mar 02 2017
STATUS
approved