Using the recursive definition

exp(f) = 1 + int(f' *exp(f))

we can make the computation of the exponential almost the same as a single multiplication.

The drawback is that we do not benefit from the error handling in compose.

Depends on #34552
Depends on #34636

CC: @tscrim

Component: combinatorics

Keywords: LazyPowerSeries

Author: Martin Rubey

Branch/Commit: 5020b9d

Reviewer: Travis Scrimshaw

Issue created by migration from https://trac.sagemath.org/ticket/34611