Neil, seqfans, Just two examples: A053879 n^2 mod 7. (* perodicity not mentioned *) A070472 n^3 mod 7. (* perodicity not mentioned *) In general, keyword "cyclic" or "periodic" may be added, right? Zak __________________________________________________ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com