OFFSET
0,3
MATHEMATICA
nmax = 21; T = PadRight[CoefficientList[# + O[y]^(nmax+1), y], nmax+1]& /@ CoefficientList[1 + 2 x (x+1)/(Sqrt[1 - 4 y] - 2 x (x+1) + 1) + O[x]^(nmax+1), x];
a[n_] := T[[n + 1, n + 1]];
Table[a[n], {n, 0, nmax}] (* Jean-François Alcover, Jul 21 2019 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Peter Luschny, Mar 18 2019
STATUS
approved