after checking some previously posted messages, it seems that a better
way to achieve your goal is to use a function definition,
(%i1) display2d : false;
(%o1) FALSE
(%i2) f(x) :=
if x=1 then 1/(1+s)
else (1+f(x-1)*s)/(1+s*(1+f(x-1)));
(%o2) f(x):=IF x = 1 THEN 1/(1+s) ELSE (1+f(x-1)*s)/(1+s*(1+f(x-1)))
(%i3) f(1);
(%o3) 1/(s+1)
(%i4) f(2);
(%o4) (s/(s+1)+1)/(s*(1/(s+1)+1)+1)
(%i5) radcan(f(2));
(%o5) (2*s+1)/(s^2+3*s+1)
(%i6) radcan(f(10));
(%o6) (10*s^9+165*s^8+792*s^7+1716*s^6+2002*s^5+1365*s^4+560*s^3+136*s^2
+18*s
+1)
/(s^10+55*s^9+495*s^8+1716*s^7+3003*s^6+3003*s^5+1820*s^4+680*s^3
+153*s^2+19*s+1)
Miquel