1. A computer-implemented method for registering an event, the method comprising: detecting occurrence of at least one event to be registered in a sequence, the sequence to have entries for occurred events, each of the entries including a number indicating a number of occurrences of at least one of the occurred events and being associated with an aggregation number reflecting a number of times the entry has been aggregated within the sequence; identifying a new entry for extending the sequence, the new entry including a first number corresponding to the detected at least one event; revising the sequence including adding the numbers of at least two entries whose respective aggregation numbers satisfy a criterion for aggregation; and storing the revised sequence.