Not an accident. Maths is philosophy in the same sense that physics is philosophy (in fact it was called "natural philosophy"): both are subsets of the general thing.
Philosophy is the "science of everything", and as such, all fields of (western, academic) knowledge are considered parts of it. Math in particular is formally equivalent to logic, which is the universal language on which philosophy is written.
Philosophy is the "science of everything", and as such, all fields of (western, academic) knowledge are considered parts of it. Math in particular is formally equivalent to logic, which is the universal language on which philosophy is written.