%I #9 May 13 2019 17:32:51
%S 1,7,17,22,43,343,381,461,543,923,1045,1182,1486,1839,5643,8260,9009,
%T 10947,11793,15915,25151
%N Numbers k such that binomial(6k, k) - 1 is prime.
%C a(22) > 50000. - _Robert Price_, May 13 2019
%t Do[f=Binomial[6n, n]-1; If[PrimeQ[f], Print[n]], {n, 1, 1000}]
%Y Cf. A125245 = numbers n such that binomial(6n, n) + 1 is prime. Cf. A066699 = numbers n such that binomial(2n, n) + 1 is prime. Cf. A066726 = numbers n such that binomial(2n, n) - 1 is prime. Cf. A125220, A125221, A125240, A125241, A125242, A125243.
%K hard,more,nonn
%O 1,2
%A _Alexander Adamchuk_, Nov 25 2006
%E More terms from _Ryan Propper_, Mar 28 2007
%E a(18)-a(21) from _Robert Price_, May 13 2019