I am trying to expand some expansion in series before extracting a given coefficient. However, I face the following problem :
In:= Clear[x, c, y]
In:= Coefficient[(c + O[y]^2)*x, x]
In:= Coefficient[(c*x) + O[x]^2, x]
In:= Coefficient[(c + O[y]^2)*x + O[x]^2, x]
Does someone have a clue where this comes from ?
Thanks a lot in advance !