/usr/lib/slepcdir/3.4.2/include/ is in libslepc3.4.2-dev 3.4.2.dfsg-1build1.
This file is owned by root:root, with mode 0o755.
..
/usr/lib/slepcdir/3.4.2/include/finclude/
/usr/lib/slepcdir/3.4.2/include/finclude/slepc.h
/usr/lib/slepcdir/3.4.2/include/finclude/slepc.h90
/usr/lib/slepcdir/3.4.2/include/finclude/slepcdef.h
/usr/lib/slepcdir/3.4.2/include/finclude/slepcds.h
/usr/lib/slepcdir/3.4.2/include/finclude/slepcds.h90
/usr/lib/slepcdir/3.4.2/include/finclude/slepcdsdef.h
/usr/lib/slepcdir/3.4.2/include/finclude/slepceps.h
/usr/lib/slepcdir/3.4.2/include/finclude/slepceps.h90
/usr/lib/slepcdir/3.4.2/include/finclude/slepcepsdef.h
/usr/lib/slepcdir/3.4.2/include/finclude/slepcfn.h
/usr/lib/slepcdir/3.4.2/include/finclude/slepcfn.h90
/usr/lib/slepcdir/3.4.2/include/finclude/slepcfndef.h
/usr/lib/slepcdir/3.4.2/include/finclude/slepcip.h
/usr/lib/slepcdir/3.4.2/include/finclude/slepcip.h90
/usr/lib/slepcdir/3.4.2/include/finclude/slepcipdef.h
/usr/lib/slepcdir/3.4.2/include/finclude/slepcmfn.h
/usr/lib/slepcdir/3.4.2/include/finclude/slepcmfn.h90
/usr/lib/slepcdir/3.4.2/include/finclude/slepcmfndef.h
/usr/lib/slepcdir/3.4.2/include/finclude/slepcnep.h
/usr/lib/slepcdir/3.4.2/include/finclude/slepcnep.h90
/usr/lib/slepcdir/3.4.2/include/finclude/slepcnepdef.h
/usr/lib/slepcdir/3.4.2/include/finclude/slepcqep.h
/usr/lib/slepcdir/3.4.2/include/finclude/slepcqep.h90
/usr/lib/slepcdir/3.4.2/include/finclude/slepcqepdef.h
/usr/lib/slepcdir/3.4.2/include/finclude/slepcst.h
/usr/lib/slepcdir/3.4.2/include/finclude/slepcst.h90
/usr/lib/slepcdir/3.4.2/include/finclude/slepcstdef.h
/usr/lib/slepcdir/3.4.2/include/finclude/slepcsvd.h
/usr/lib/slepcdir/3.4.2/include/finclude/slepcsvd.h90
/usr/lib/slepcdir/3.4.2/include/finclude/slepcsvddef.h
/usr/lib/slepcdir/3.4.2/include/finclude/slepcsys.h
/usr/lib/slepcdir/3.4.2/include/finclude/slepcsysdef.h
/usr/lib/slepcdir/3.4.2/include/slepc-private/
/usr/lib/slepcdir/3.4.2/include/slepc-private/dsimpl.h
/usr/lib/slepcdir/3.4.2/include/slepc-private/epsimpl.h
/usr/lib/slepcdir/3.4.2/include/slepc-private/fnimpl.h
/usr/lib/slepcdir/3.4.2/include/slepc-private/ipimpl.h
/usr/lib/slepcdir/3.4.2/include/slepc-private/mfnimpl.h
/usr/lib/slepcdir/3.4.2/include/slepc-private/nepimpl.h
/usr/lib/slepcdir/3.4.2/include/slepc-private/qepimpl.h
/usr/lib/slepcdir/3.4.2/include/slepc-private/slepcimpl.h
/usr/lib/slepcdir/3.4.2/include/slepc-private/stimpl.h
/usr/lib/slepcdir/3.4.2/include/slepc-private/svdimpl.h
/usr/lib/slepcdir/3.4.2/include/slepc-private/vecimplslepc.h
/usr/lib/slepcdir/3.4.2/include/slepc.h
/usr/lib/slepcdir/3.4.2/include/slepcblaslapack.h
/usr/lib/slepcdir/3.4.2/include/slepcconf.h
/usr/lib/slepcdir/3.4.2/include/slepcds.h
/usr/lib/slepcdir/3.4.2/include/slepceps.h
/usr/lib/slepcdir/3.4.2/include/slepcfn.h
/usr/lib/slepcdir/3.4.2/include/slepcip.h
/usr/lib/slepcdir/3.4.2/include/slepcmath.h
/usr/lib/slepcdir/3.4.2/include/slepcmfn.h
/usr/lib/slepcdir/3.4.2/include/slepcnep.h
/usr/lib/slepcdir/3.4.2/include/slepcqep.h
/usr/lib/slepcdir/3.4.2/include/slepcst.h
/usr/lib/slepcdir/3.4.2/include/slepcsvd.h
/usr/lib/slepcdir/3.4.2/include/slepcsys.h
/usr/lib/slepcdir/3.4.2/include/slepcvec.h
/usr/lib/slepcdir/3.4.2/include/slepcversion.h
/usr/lib/slepcdir/3.4.2/include/src/
/usr/lib/slepcdir/3.4.2/include/src/eps/
/usr/lib/slepcdir/3.4.2/include/src/eps/impls/
/usr/lib/slepcdir/3.4.2/include/src/eps/impls/arpack/
/usr/lib/slepcdir/3.4.2/include/src/eps/impls/arpack/arpackp.h
/usr/lib/slepcdir/3.4.2/include/src/eps/impls/blopex/
/usr/lib/slepcdir/3.4.2/include/src/eps/impls/blopex/slepc-interface.h