OFFSET
0,2
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..500
FORMULA
O.g.f.: ( 1 - x*G(2*x) - sqrt( (1 - x*G(2*x))^2 - 8*x ) )/(4*x) = (3 + sqrt(1-8*x) - sqrt(10 - 136*x + 6*sqrt(1-8*x)))/(16*x), where G(x)=(1-sqrt(1-4*x))/(2*x) is o.g.f. for Catalan numbers A000108.
MATHEMATICA
CoefficientList[Series[(3 + Sqrt[1 - 8*x] - Sqrt[10 - 136*x + 6*Sqrt[1 - 8*x]])/(16*x), {x, 0, 50}], x] (* G. C. Greubel, Apr 20 2016 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Max Alekseyev, Oct 02 2009
STATUS
approved