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Primes of the form x^2 + (x+3)^2.
3

%I #16 Aug 22 2024 02:04:48

%S 17,29,89,149,269,317,617,929,1109,1409,2969,3449,3617,4517,5309,6389,

%T 7817,8069,8849,12329,14969,17117,17489,21017,23117,23549,27617,30509,

%U 32009,33029,34589,35117,41189,42929,43517,47129,48989,52817,60209

%N Primes of the form x^2 + (x+3)^2.

%C Each prime of the form 4k+1 has a unique representation as x^2+y^2; these primes have y-x=3.

%H Vincenzo Librandi, <a href="/A076727/b076727.txt">Table of n, a(n) for n = 1..1000</a>

%t Select[Table[2*n^2+6*n+9,{n,0,300}],PrimeQ] (* _Vincenzo Librandi_, Jul 15 2012 *)

%o (Magma) [a: n in [0..200] | IsPrime(a) where a is 2*n^2+6*n+9]; // _Vincenzo Librandi_, Jul 15 2012

%Y Cf. A002144, A027862.

%K easy,nonn

%O 1,1

%A _Cino Hilliard_, Oct 28 2002

%E Edited by _Don Reble_, May 03 2006