Let ad be the number of non-negative integer solutions (a,b) to a+b=d where a≡b (mod n) for a fixed n∈Z+. Consider the generating function M(t)=a0+a1t+a2t2+... Consider
P(n)=t→1lim(nM(t)−(1−t)21).
Then P(n), n∈Z+ is a polynomial in n, so we can extend its domain to include all real numbers while having it remain a polynomial. Find P(0).