sentences:  These generators do not always generate sequences which are sufficiently random, but instead can produce sequences which contain patterns.For example, the infamous RANDU routine fails many randomness tests dramatically, including the spectral test.Stephen Wolfram used randomness tests on the output of Rule 30 to examine its potential for generating random numbers, though it was shown to have an effective key size far smaller than its actual size and to perform poorly on a chi-squared test.