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 A112855 Numbers n such that (2*n)!/n!+1 is prime. 5
 1, 2, 5, 10, 24, 30, 72, 340, 379, 712, 1020, 1647, 3654, 7923 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS Next term is > 10000. LINKS MATHEMATICA Select[Range[8000], PrimeQ[(2#)!/#!+1]&] (* Harvey P. Dale, Mar 23 2012 *) CROSSREFS 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. Sequence in context: A297074 A099963 A152784 * A299436 A049937 A026754 Adjacent sequences:  A112852 A112853 A112854 * A112856 A112857 A112858 KEYWORD hard,nonn AUTHOR Hugo Pfoertner, Sep 25 2005 STATUS approved

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Last modified September 23 13:34 EDT 2020. Contains 337310 sequences. (Running on oeis4.)