George Andrews and Bruce Berndt have written five books about Ramanujan's lost notebook, which was actually not a notebook but a pile of notes Andrews found in 1976 in a box at the Wren Library at Trinity College, Cambridge. In 2019 Berndt wrote about the last unproved identity in the lost notebook:

Following Timothy Chow's advice, I consulted Berndt and asked him if there were any remaining formulas of Ramanujan that have neither been proved nor disproved. He said *no*:

To the best of my knowledge, there are no claims or conjectures remaining. There are some statements to which we have not been able to attach meaning.

I checked to make sure that this applies to *all* of Ramanujan's output, not just the lost notebook, and he said yes.

**EDIT**: However, only on December 21st, 2021 did Örs Rebák submit this paper to the arXiv:

in which he completed an *incomplete* formula in Ramanujan's lost notebook, and proved it. So there may still be gems left to polish.

whichproblem has a positive answer? $\endgroup$7more comments