numerus_perfectus sigma1 6 28 496 8128 Measured time: 53.1678 second(s) sigma2 6 28 496 8128 Measured time: 29.7022 second(s) sigma3 6 28 496 8128 Measured time: 28.4608 second(s) sigma4 6 28 496 8128 Measured time: 5.04254 second(s) OK!