invert power series?



Hello,
  I have a power series of the form

x(t) = a[1]*t + a[2]*t^2 + . . .

with a[1] different from 0.

and I would like to invert it to the series

t(x) = b[1]*x + b[2]*x^2 + . . .

Are there built-in maxima routines which can be used to do this.  I
know I can write my own recursion, but I want to know if this is
already part of the maxima code.

TIA,
  -sen


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