A065347 Positions of zeros in A065344, i.e., binomial(2n,n) mod ((n+1)*(n+2)) = 0.

3, 5, 8, 9, 11, 12, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 26, 27, 29, 32, 33, 35, 36, 38, 39, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 80, 81, 83, 84, 86, 87, 89, 90

Offset: 1

Author

Labos Elemer, Oct 30 2001

Keywords

• nonn

Links

• Harry J. Smith, Table of n, a(n) for n = 1..1000
• C. Pomerance, Divisors of the middle binomial coefficient, Amer. Math. Monthly, 112 (2015), 636-644.

Crossrefs

Cf. A000108, A065344, A065345, A065346, A065348, A065349.

Programs

Mathematica

ris = {}; Do[If[Mod[Binomial[2 n, n], (n + 1) (n + 2)] == 0, AppendTo[ris, n]], {n, 100}]; ris (* Bruno Berselli, Jan 06 2014 *)

PARI

isok(k) = { binomial(2*k, k) % ((k + 1)*(k + 2)) == 0 } \\ Harry J. Smith, Oct 17 2009