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Primes p such that p-+floor(Sqrt(p)) are primes.
2

%I #2 Mar 31 2012 12:38:28

%S 5,37,47,151,331,349,593,617,907,911,937,941,1789,1831,2341,2389,2399,

%T 2957,3617,3631,3673,3719,4457,5261,5309,6121,6151,6199,6221,7103,

%U 7127,7213,8101,8179,9323,9337,9377,10529,10589,11789,13007,13033,13037

%N Primes p such that p-+floor(Sqrt(p)) are primes.

%C 5-+2->primes, 37-+6->primes,..

%t f1[n_]:=n-Floor[Sqrt[n]];f2[n_]:=n+Floor[Sqrt[n]];lst={};Do[p=Prime[n];If[PrimeQ[f1[p]]&&PrimeQ[f2[p]],AppendTo[lst,p]],{n,8!}];lst

%Y Cf. A086085, A086086

%K nonn

%O 1,1

%A _Vladimir Joseph Stephan Orlovsky_, Feb 25 2010