A153788 Number of proper divisors of the Catalan number A000108(n).

0, 0, 1, 1, 3, 7, 11, 7, 15, 15, 23, 31, 47, 71, 191, 95, 191, 255, 575, 511, 767, 767, 1023, 1151, 1151, 1727, 1535, 1535, 4095, 4095, 5119, 2047, 6143, 12287, 12287, 8191, 12287, 12287, 24575, 24575, 36863, 98303, 131071, 147455

Offset: 0

Author

Omar E. Pol, Jan 18 2009

Keywords

• nonn

Links

• G. C. Greubel, Table of n, a(n) for n = 0..1000

Crossrefs

Cf. A000108, A032741, A152762, A152763, A152988.

Programs

Mathematica

DivisorSigma[0, CatalanNumber@Range[0, 1000]] - 1 (* G. C. Greubel, Aug 28 2016 *)

PARI

a(n)=numdiv(binomial(2*n,n)/(n+1)) - 1 \\ Charles R Greathouse IV, Aug 29 2016

Formula

a(n) = A032741(A000108(n)) = A152763(n) - 1.