/usr/include/regina-normal/maths/ is in regina-normal-dev 4.95-1build1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/regina-normal/maths/approx.h
/usr/include/regina-normal/maths/matrixops.h
/usr/include/regina-normal/maths/ninteger.h
/usr/include/regina-normal/maths/nlargeinteger.h
/usr/include/regina-normal/maths/nmatrix.h
/usr/include/regina-normal/maths/nmatrix2.h
/usr/include/regina-normal/maths/nmatrixint.h
/usr/include/regina-normal/maths/nperm3.h
/usr/include/regina-normal/maths/nperm4.h
/usr/include/regina-normal/maths/nperm5.h
/usr/include/regina-normal/maths/nprimes.h
/usr/include/regina-normal/maths/nrational.h
/usr/include/regina-normal/maths/nray.h
/usr/include/regina-normal/maths/numbertheory.h
/usr/include/regina-normal/maths/nvector.h
/usr/include/regina-normal/maths/permconv.h