def NeighborIDs(neighbor_ids: list, atomic_nums: list, y: list) -> list:
    """Find neighbor ids of a list of atoms (Hs not included)."""

    # neighbor ids
    z = [neighbor_ids[x] for x in y]

    # remove Hs
    return [[x for x in y if atomic_nums[x] != 1] for y in z]