OFFSET
0,4
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
FORMULA
a(n) = floor(sqrt(trinomial(2*n,n))).
MATHEMATICA
FSFromSeries[f_, x_, n_] := Map[Floor[Sqrt[#]]&, CoefficientList[Series[f, {x, 0, n}], x]]
FSFromSeries[1/Sqrt[1-2x-3x^2], x, 100]
CROSSREFS
KEYWORD
nonn
AUTHOR
Emanuele Munarini, Jul 07 2011
STATUS
approved