This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A112863 #31 Jul 24 2024 17:33:24 %S A112863 1,3,5,6,14,19,24,45,49,62,72,122,149,197,209,222,349,409,491,527,601, %T A112863 675,728,769,795,853,1039,1318,1599,2069,2279,2567,2634,3286,3482, %U A112863 6880,6919,9117,9276,9564,10898,13061,14570,16493,17366,18773,19901,25569,26611,28322 %N A112863 Numbers k such that (2*k)!/(2*(k!)^2)+1 is prime. %t A112863 Select[Range[3000],PrimeQ[(2#)!/(2(#!)^2)+1]&] (* _James C. McMahon_, Jun 13 2024 *) %o A112863 (PARI) isok(k) = ispseudoprime(1+binomial(2*k-1, k-1)); \\ _Michel Marcus_, Jun 14 2024 %Y A112863 Cf. A001700, A112864, A112853, A112855, A066726, A112861. %K A112863 hard,nonn %O A112863 1,2 %A A112863 _Hugo Pfoertner_, Sep 30 2005 %E A112863 a(42)-a(43) from _Charles R Greathouse IV_, Sep 26 2006 %E A112863 a(44)-a(50) from _Michael S. Branicky_, Jul 24 2024