How to find a math conference accepting papers?
In mathematics, you're very unlikely to find such a conference.  There are a few (the only one that springs to mind is FPSAC).  There are sometimes proceedings based on conferences, but typically those articles are solicited after the conference from the invited speakers.  The idea of taking submissions of papers before conferences and then judging whether they are appropriate for presentation at the conference is pretty foreign to mathematicians, and publishing in conference proceedings is much lower in prestige than in journals.

Thus, I recommend you submit to a journal instead.