OFFSET
2,1
COMMENTS
Same as A104722 except for leading term (both have rational g.f.s). - R. J. Mathar and Franklin T. Adams-Watters, May 19 2008
LINKS
G. C. Greubel, Table of n, a(n) for n = 2..1000
F. R. Bernhart, Catalan, Motzkin and Riordan numbers, Discr. Math., 204 (1999), 73-112.
FORMULA
G.f.: 1 + ( (1 + x)*(1 - Sqrt[1 - 4*x^2])/(2*x^2))^2. - G. C. Greubel, Jan 08 2017
MATHEMATICA
CoefficientList[Series[1 + ( (1 + x)*(1 - Sqrt[1 - 4*x^2])/(2*x^2))^2, {x, 0, 50}], x] (* G. C. Greubel, Jan 08 2017 *)
PROG
(PARI) Vec( 1 + ( (1 + x)*(1 - sqrt(1 - 4*x^2))/(2*x^2))^2 + O(x^25)) \\ G. C. Greubel, Jan 08 2017
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Jan 27 2001
STATUS
approved