Answer
nonnegative integer
real
Work Step by Step
The nonnegative integers are: $1,2,3,...$
Notice that $a_0,a_1,...,a_n$ must be real numbers, but the zeros can be a complex number.
You can help us out by revising, improving and updating this answer.
Update this answerAfter you claim an answer you’ll have 24 hours to send in a draft. An editor will review the submission and either publish your submission or provide feedback.