A165566 - OEIS

%I #11 Sep 08 2022 08:45:48

%S 17,23,31,47,73,79,103,113,127,151,167,193,199,233,241,311,313,337,

%T 401,433,479,503,521,569,577,601,631,647,719,809,823,839,863,887,911,

%U 919,953,1031,1049,1087,1129,1151,1193,1201,1217,1231,1249,1303,1433,1439,1487

%N Primes p such that (p^2-1)/8-p is also prime.

%H Vincenzo Librandi, <a href="/A165566/b165566.txt">Table of n, a(n) for n = 1..1000</a>

%F (a(n)^2-1)/8-a(n) = A165567(n).

%e For p=17, (17^2-1)/8-17=19 is prime, which adds p=17 to the sequence.

%e For p=23, (23^2-1)/8-23=43 is prime, which adds p=23 to the sequence.

%t Select[Prime[Range[5, 1000]], PrimeQ[(#^2 - 1) / 8 - #]&] (* _Vincenzo Librandi_, Apr 10 2013 *)

%o (Magma) [p: p in PrimesInInterval(7, 1500) | IsPrime(((p^2-1) div 8) - p)]; // _Vincenzo Librandi_, Apr 10 2013

%Y Cf. A165567.

%K nonn,easy

%O 1,1

%A _Vincenzo Librandi_, Sep 22 2009

%E Edited and extended by _R. J. Mathar_, Sep 25 2009