A065346 a(n) = binomial(2*n, n) mod ((n+1)*(n+2)*(n+3)*(n+4)).

2, 6, 20, 70, 252, 924, 3432, 990, 14300, 16588, 17472, 39676, 4760, 18360, 46512, 29070, 30780, 87780, 0, 191268, 273240, 322920, 140400, 58500, 190008, 350784, 402752, 611320, 81840, 649264, 41888, 164934, 264180, 295260, 1316016, 694564

Offset: 1

Author

Labos Elemer, Oct 30 2001

Keywords

• nonn

Links

• Chai Wah Wu, Table of n, a(n) for n = 1..10000 (terms 1..1000 from Harry J. Smith)
• C. Pomerance, Divisors of the middle binomial coefficient, Amer. Math. Monthly, 112 (2015), 636-644.

Crossrefs

Cf. A000108, A065344, A065345, A065347, A065348, A065349.

Programs

Mathematica

Table[Mod[Binomial[2 n, n], (n + 1) (n + 2) ((n + 3) (n + 4))], {n, 100}] (* Bruno Berselli, Jan 06 2014 *)

PARI

a(n) = { binomial(2*n, n) % ((n + 1)*(n + 2)*(n + 3)*(n + 4)) } \\ Harry J. Smith, Oct 17 2009