Pfaff transformation
= Pfaff transformation
{c}
With compatible branches and initially near $z=0$,
$$
F\left(a,c-b;c;\frac{z}{z-1}\right)
=(1-z)^aF(a,b;c;z).
$$
It follows by applying a Möbius transformation and a dependent-variable rescaling to the same <Papperitz symbol>, then matching the normalized analytic solution at zero.