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A153788
Number of proper divisors of the Catalan number A000108(n).
1
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
0,5
LINKS
FORMULA
a(n) = A032741(A000108(n)) = A152763(n) - 1.
MATHEMATICA
DivisorSigma[0, CatalanNumber@Range[0, 1000]] - 1 (* G. C. Greubel, Aug 28 2016 *)
PROG
(PARI) a(n)=numdiv(binomial(2*n, n)/(n+1)) - 1 \\ Charles R Greathouse IV, Aug 29 2016
CROSSREFS
KEYWORD
nonn
AUTHOR
Omar E. Pol, Jan 18 2009
STATUS
approved