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%I #6 Nov 21 2013 12:48:45
%S 1,2,5,10,24,30,72,340,379,712,1020,1647,3654,7923
%N Numbers n such that (2*n)!/n!+1 is prime.
%C Next term is > 10000.
%t Select[Range[8000],PrimeQ[(2#)!/#!+1]&] (* _Harvey P. Dale_, Mar 23 2012 *)
%Y Cf. A112856 primes of the form (2*n)!/n!+1, A112853 (2*n)!/n!-1 is prime, A066726 (2*n)!/(n!)^2-1 is prime, A112859 (2*n)!/(n!)^2+1 is prime, A112861 (2*n)!/(2*(n!)^2)-1 is prime, A112863 (2*n)!/(2*(n!)^2)+1 is prime.
%K hard,nonn
%O 1,2
%A _Hugo Pfoertner_, Sep 25 2005
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