A125243 Numbers k such that binomial(5k, k) + 1 is prime.

0, 22, 86, 154, 160, 488, 705, 958, 975, 1262, 1932, 2845, 12718, 14434, 20337, 38834, 40433, 44874, 68279, 68724, 89911, 104765

Offset: 1

Author

Alexander Adamchuk, Nov 25 2006

Keywords

• hard
• more
• nonn

Comments

a(22) > 100000. - Robert Price, Mar 20 2025

Crossrefs

Cf. A125242, A066699, A066726.

Cf. A125220, A125221, A125240, A125241, A125244, A125245.

Programs

Mathematica

Do[f=Binomial[5n, n]+1; If[PrimeQ[f], Print[n]], {n, 1, 1000}]

Extensions

More terms from Ryan Propper, Jan 05 2007

a(1)=0 prepended and a(13)-a(18) added by Robert Price, May 11 2019

a(19)-a(21) from Robert Price, Mar 20 2025

a(22) from Georg Grasegger, May 06 2025