/usr/include/ is in libpari-dev 2.7.5-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/x86_64-linux-gnu/
/usr/include/x86_64-linux-gnu/pari/
/usr/include/x86_64-linux-gnu/pari/mpinl.h
/usr/include/x86_64-linux-gnu/pari/paritune.h
/usr/include/x86_64-linux-gnu/pari/parimt.h
/usr/include/x86_64-linux-gnu/pari/pari.h
/usr/include/x86_64-linux-gnu/pari/parierr.h
/usr/include/x86_64-linux-gnu/pari/parisys.h
/usr/include/x86_64-linux-gnu/pari/paridecl.h
/usr/include/x86_64-linux-gnu/pari/parigen.h
/usr/include/x86_64-linux-gnu/pari/pariold.h
/usr/include/x86_64-linux-gnu/pari/paricom.h
/usr/include/x86_64-linux-gnu/pari/paricfg.h
/usr/include/x86_64-linux-gnu/pari/paristio.h
/usr/include/x86_64-linux-gnu/pari/paripriv.h
/usr/include/x86_64-linux-gnu/pari/pariinl.h
/usr/include/x86_64-linux-gnu/pari/parinf.h
/usr/include/x86_64-linux-gnu/pari/paricast.h
/usr/include/x86_64-linux-gnu/pari/genpari.h