OFFSET
0,2
COMMENTS
LINKS
Robert Israel, Table of n, a(n) for n = 0..1663
FORMULA
Numerators of the rationals r(n) = binomial(2n,n)/(2n+1) with G.f.: 1/(2*sqrt(x))*arcsin(2*sqrt(x)). [Vladimir Kruchinin, May 31 2013]
EXAMPLE
The rationals r(n) begin: 1, 2/3, 6/5, 20/7, 70/9, 252/11, 924/13, 1144/5, 12870/17, ...
MAPLE
seq(numer(binomial(2*n, n)/(2*n+1)), n=0..50); # Robert Israel, Feb 21 2017
MATHEMATICA
Numerator[Table[Binomial[2n, n]/(2n+1), {n, 0, 30}]] (* Harvey P. Dale, Jul 25 2013 *)
PROG
(PARI) a(n) = numerator(binomial(2*n, n)/(2*n+1)) \\ Felix Fröhlich, Feb 21 2017
CROSSREFS
KEYWORD
nonn,frac
AUTHOR
N. J. A. Sloane, Aug 28 2000
STATUS
approved