A144046 - OEIS

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A144046

Numbers n such that |n!-107| and |n!+107| are prime.

%I #5 May 13 2013 01:48:59

%S 3,4,5,6,7,8,80

%N Numbers n such that |n!-107| and |n!+107| are prime.

%F 5!-107=13 and 5!+107=227, so 5 is a member.

%t lst={};a=107;Do[If[PrimeQ[n!-a]&&PrimeQ[n!+a],AppendTo[lst,n]],{n,0,20^2}];lst

%o (PARI) for(n=1,106,if(ispseudoprime(abs(n!-107))&&ispseudoprime(n!+107),print1(n", "))) \\ _Charles R Greathouse IV_, Oct 05 2011

%K nonn,fini,full

%O 1,1

%A _Vladimir Joseph Stephan Orlovsky_, Sep 08 2008