OFFSET
0,2
LINKS
Colin Barker, Table of n, a(n) for n = 0..300
FORMULA
a(n) = A006318(2n).
a(n) = Sum_{i=0..2n} (C(2*n+1,i+1)*C(2*n+i,i))/(2*n+1). - Vladimir Kruchinin, Apr 02 2017
D-finite with recurrence +n*(2*n+1)*a(n) +(-70*n^2+73*n-15)*a(n-1) +(70*n^2-277*n+270)*a(n-2) -(2*n-5)*(n-3)*a(n-3)=0. - R. J. Mathar, Mar 25 2024
PROG
(Maxima)
a(n):=sum(binomial(2*n+1, i+1)*binomial(2*n+i, i), i, 0, 2*n)/(2*n+1); /* Vladimir Kruchinin, Apr 02 2017 */
(PARI) a(n) = sum(i=0, 2*n, binomial(2*n+1, i+1)*binomial(2*n+i, i))/(2*n+1) \\ Colin Barker, Dec 28 2017
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
N. J. A. Sloane, May 08 2008
STATUS
approved