Forms of probability-density functions obtainable from summed m sequences

The letter discusses the sums of m sequences generated by a feedback shift register where the summed sequences are not necessarily from successive stages. A method for obtaining all the possible probability-density functions is given. The particular case of five stages is studied in detail. It is found that, for this case and a number of other cases tested, the rth moment (or central moment) is identical for all the situations in which there are at least r interdependent stages in the sum.