Publishing a mathematical research article on research which is already done?
An article is not about you. It is not a reward of effort. In an article you try to communicate to the readers, so it needs to contain something that your readers want to read. If something is already done, then why would I want to read it? Maybe, you have variation, or a special case, or a more general case, that makes your equation or your derivation thereof different and interesting. But if that is not the case, then the answer is simply no.