That sounds mighty weird, and honestly the statement has certain characteritics that trigger my crackpot alarm (don’t take it personally)... If what you say is true, it’s not like you don’t have recourse — you can write to the publication’s editorial board, or report to your department or institution’s academic disciplinary body (of course, that’s after you have contacted whomever you’re in dispute with; it’s okay, and I’ve had people cold emailing me about my preprint, asking me to mention their only somewhat related and by no means appropriated work...) Also, if you produced whatever result when you were working for a professor, they can publish it under their name (it’s nice to at least have you on the author list, of course), you don’t revoke their right just by publishing it on your own website. Anyway, whining on HN is the about least useful thing you can do.

This is common stuff, and good luck on prompt action! No, I wasn't working for a prof - but note that you yourself just accept that work including ideas can be published by a prof without attribution to the discoverer! That tells us all where the academic mindset is. My noting is your whining, I gather. One can't tarry on life's path to upbraid all the assholes in the world, and legal redress is well out of reach of most of us. One can note it to warn others, and move on.

Sad to hear that.

What kind of work was that?