It is proved that there are precisely 4204 pairwise non-isomorphic Steiner systems S(5, 6, 72) invariant under the group PSL2(71) and which can be constructed using only short orbits. It is further proved that there are precisely 38717 pairwise non-isomorphic Steiner systems S(5, 6, 84) invariant under the group PSL2(83) and which can be constructed using only short orbits.
Mike J. Grannell, Terry S. Griggs, Rudolf Mathon