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%I A082672 #27 Sep 08 2022 08:45:10
%S A082672 2,4,5,7,8,13,16,30,43,49,91,119,213,1380,1637,2258,4647,9701,12258
%N A082672 Numbers n such that (n! + 2)/2 is a prime.
%t A082672 Select[Range[10^2], PrimeQ[(#!+2)/2] &] (* _Vladimir Joseph Stephan Orlovsky_, Apr 29 2008 *)
%o A082672 (PARI) \\ x such that (x!+2)/2 is prime
%o A082672 xfactpk(n,k=2) = { for(x=2,n, y = (x!+k)/k; if(isprime(y),print1(x, ", ")) ) }
%o A082672 (Magma) [ n: n in [1..300] | IsPrime((Factorial(n)+2) div 2) ];
%Y A082672 Cf. A089130.
%Y A082672 Cf. n!/m-1 is a prime: A002982, A082671, A139056, A139199-A139205; n!/m+1 is a prime: A002981, A082672, A089085, A139061, A139058, A139063, A139065, A151913, A137390, A139071 (1<=m<=10).
%K A082672 easy,nonn
%O A082672 1,1
%A A082672 _Cino Hilliard_, May 18 2003
%E A082672 More terms from _Don Reble_, Dec 08 2003
%E A082672 More terms from Herman Jamke (hermanjamke(AT)fastmail.fm), Jan 03 2008

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