> **Possible Duplicate:**  
> [What recent discoveries have amateur mathematicians made?](https://mathoverflow.net/questions/44244/what-recent-discoveries-have-amateur-mathematicians-made)  


Dear overflowers

Out of curiosity: do you know any famous papers and/or results by non professional mathematicians? (I realize that 'non professional mathematicians' is quite vague, so let's also say 'amateur'?)
Thank you for your answers!

**Edit:** I meant of course math papers. Also, I am interested in somewhat recent examples, say the last 2 centuries.