(05/01/2010, 03:21 PM)tommy1729 Wrote: dear mike

the regular interval that you seek has been computed by andy.

its somewhere here on this forum.

Lazy boy!

Andrew gave a rough overview of the behavior of the higher operations here.

Due to the fact that (below identity) for and (above identity), tetration always (for every base) has a lower fixed point (I guess this is true for every even rank), which can be used for regular iteration giving a pentation (or the odd rank above).

Interesting question would indeed be for which bases pentation has a lower fixed point (but indeed I think this was computed already on the forum, perhaps do a search for pentation).