Sorry for this apparently simple question but I’m unable to find an answer on google or in the docs.

I already know the formal power series of a function. And I’m able to construct a SeqFormula whose terms match this expansion.

Now I’d like to compute multiplication, and inverse, of this formal series. From the doc it seems the FormalPowerSeries class supports exactly what I want, but there is no documented way to actually construct a FormalPowerSeries object.

Can I ask how to construct a FormalPowerSeries object from a known expansion?