Mostly interested in integer(/prime) factorisation, specifically of large semi-primes (the hardest instance). Work which usually involves finding/developing algorithms that use algebra and modular arithmetic. Also interested in the work of Diophantus, and the work of Jacques Ozanam on generalising Diophantus's results:

https://archive.org/details/MSR.144 https://archive.org/details/MSR.145