{c}

Numerical solution:
``
427278142
``

Earliest known public leak:
* https://github.com/lucky-bai/projecteuler-solutions/issues/104

Programs:
* https://github.com/cirosantilli/project-euler-solutions/blob/master/solvers/973.py

Explanation: https://github.com/cirosantilli/project-euler-solutions/blob/master/solvers/973.md

Notes:
* https://matharena.ai/?comp=euler--euler from <MathArena> claims <Gemini 3> solved it
* https://x.com/roanoke_gal/status/1997322744594125081 claims <GPT-5.1 Pro> solved it.


 Project Euler problem 973 solution

ID: project-euler-problem-973-solution