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%I #31 Jul 24 2024 17:33:24
%S 1,3,5,6,14,19,24,45,49,62,72,122,149,197,209,222,349,409,491,527,601,
%T 675,728,769,795,853,1039,1318,1599,2069,2279,2567,2634,3286,3482,
%U 6880,6919,9117,9276,9564,10898,13061,14570,16493,17366,18773,19901,25569,26611,28322
%N Numbers k such that (2*k)!/(2*(k!)^2)+1 is prime.
%t Select[Range[3000],PrimeQ[(2#)!/(2(#!)^2)+1]&] (* _James C. McMahon_, Jun 13 2024 *)
%o (PARI) isok(k) = ispseudoprime(1+binomial(2*k-1, k-1)); \\ _Michel Marcus_, Jun 14 2024
%Y Cf. A001700, A112864, A112853, A112855, A066726, A112861.
%K hard,nonn
%O 1,2
%A _Hugo Pfoertner_, Sep 30 2005
%E a(42)-a(43) from _Charles R Greathouse IV_, Sep 26 2006
%E a(44)-a(50) from _Michael S. Branicky_, Jul 24 2024
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