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A161863 Numbers n such that n^2+n+3 and n^2+n-3 are both prime. 2


%S 4,7,10,22,25,34,70,79,112,130,139,172,187,217,229,262,274,295,304,

%T 322,337,364,397,400,472,499,574,580,592,622,634,655,664,697,829,844,

%U 925,1057,1144,1165,1255,1300,1309,1357,1414,1420,1489,1537,1642,1669,1744

%N Numbers n such that n^2+n+3 and n^2+n-3 are both prime.

%e n=4 is in the list because 20+-3 are primes. n=7 is in the list because 56+-3 are primes.

%t q=3;lst3={};Do[p=n^2+n;If[PrimeQ[p-q]&&PrimeQ[p+q],AppendTo[lst3,n]],{n,0,7!}];lst3

%Y Cf. A088485

%K nonn,easy

%O 1,1

%A _Vladimir Joseph Stephan Orlovsky_, Jun 20 2009

%E Definition rephrased by _R. J. Mathar_, Jun 27 2009

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Last modified June 19 06:47 EDT 2019. Contains 324218 sequences. (Running on oeis4.)