Asking for recommendation letters for postdoc positions in mathematics I'm starting my fifth year in math PhD. For two years I've been thinking on a well known problem (well known enough to have a Wikipedia page) in my field with no success  and all of a sudden I think I did solve it with a very short solution. I haven't written it down yet but I can do so in 1 week. The bottom line is that I'm in a situation that there is nothing positive about my CV except solving the conjecture. I do not have any other publications and I'm very unknown,no professional mathematician in my field is aware of my existence. I'm planning to apply for postdoc positions this coming fall but what I'm struggling with is the letters of recommendation. Let's say I'll write my arxiv version of the paper in 1 week and about 1 week it will take it for me to explain it to my adviser and proofread it. My adviser hopefully will help me to give some talks at some places (I haven't given any talks outside of my university during my PhD). I think the standard procedure is that after giving the talk I should start asking for the LOR from the people who attended my talk until I can get 2 LORs. Problem is that this procedure will potentially take a lot of time and as people require at least a month to write LORs by that time the deadlines will be passed. I wanted to ask for some ideas on how to get LORs in my situation?

I was thinking maybe I can send emails directly to the people in my field with my preprint and directly ask for the LOR but someone told me this is very unusual and might not be a good idea. What are your opinions on this?
Things have changed since I was about to finish a PhD a long time ago, but the fact that you are unknown outside your university would have been common then, perhaps even now. 

What you suggest seems to me to have two downsides. First, you are putting all your eggs into one basket (the conjecture) and second, you are entering into a time consuming process where others will need to verify your work. But beyond that, those others don't really know much about you beyond this one thing. 

I would suggest, instead, that you depend on your advisor for a very strong letter and on others (professors and such) with whom you have interacted and who can speak now to your general mathematical ability and future potential. That can all be done quickly and can get you into what may be just the first round of applications. 

But don't abandon your stated idea here to reach out to those others who have seen your work and might also help with an application if the more common approach seems not to be working as well as you hope. 

You can get started early and if it doesn't work out, then the longer term solution may start to fall into place for the next round.