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 A125242 #13 Nov 16 2024 21:31:22
%S A125242 5,71,111,187,239,247,473,628,847,1478,2687,3530,5175,9113,10968,
%T A125242 15039,28929,35649,43481,44455,51269,63975,71723
%N A125242 Numbers k such that binomial(5k, k) - 1 is prime.
%C A125242 a(24) > 10^5. _Robert Price_, Nov 16 2024
%t A125242 Do[f=Binomial[5n, n]-1; If[PrimeQ[f], Print[n]], {n, 1, 1000}]
%t A125242 Select[Range[45000],PrimeQ[Binomial[5#,#]-1]&] (* _Harvey P. Dale_, Jan 02 2022 *)
%Y A125242 Cf. A125243 = numbers n such that binomial(5n, 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, A125244, A125245.
%K A125242 hard,more,nonn
%O A125242 1,1
%A A125242 _Alexander Adamchuk_, Nov 25 2006
%E A125242 More terms from _Ryan Propper_, Jan 06 2007
%E A125242 a(15)-a(20) from _Robert Price_, May 03 2019
%E A125242 a(21)-a(23) from _Robert Price_, Nov 16 2024