I have a very complicated and long expression (thousands of terms) that boils down to a form of
expr = a1 Exp[b1] + a2 Exp[b2] + a3 Exp[b3]
Note that all the expressions a and b are huge symbolic expressions, but that this expression is developed in this way.
Now I would like to have a list with b1, b2, b3.
All I can do is
but that does not give me a list.