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 A145471 Primes p such that (5+p)/2 is prime. 20

%I

%S 5,17,29,41,53,89,101,113,137,173,197,257,269,293,353,389,449,461,509,

%T 521,557,617,701,761,773,797,857,881,929,953,977,1013,1109,1181,1193,

%U 1229,1277,1289,1301,1361,1433,1481,1613,1637,1709,1721,1877,1889,1901

%N Primes p such that (5+p)/2 is prime.

%C All these primes are congruent to 1 mod 4 and to 5 mod 12.

%t aa = {}; k = 5; Do[If[PrimeQ[(k + Prime[n])/2], AppendTo[aa, Prime[n]]], {n, 1, 500}];aa

%t Select[Prime[Range[500]],PrimeQ[(5+#)/2]&] *( From Harvey P. Dale, Apr 23 2011 *)

%o (PARI) forprime(p=2,1e4,if(p%12!=5,next);if(isprime(p\2+3),print1(p", "))) \\ _Charles R Greathouse IV_, Jul 16, 2011

%Y Cf. A092109.

%K nonn,changed

%O 1,1

%A _Artur Jasinski_, Oct 11 2008

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Last modified May 25 01:26 EDT 2013. Contains 225631 sequences.