  Despite many searches for periodicity in the repeating fast radio burst FRB
121102, the underlying pattern of bursts does not appear to be a periodic one.
We report a logarithmic repetition pattern in FRB 121102 in the sense that the
rate falls off inversely with time for each set of bursts. This result implies
that repeating FRB sources are not necessarily associated with a pulsar, but
rather could be caused by a different type of phenomenon that involves an equal
amount of energy output per log time.
