Let there be two particularly well-behaved functions 
and 
.
If the limit
 |
exists, then 
is a regular sequence of particularly
well-behaved functions.
Regular Sequence
See also
Ring Regular SequenceExplore with Wolfram|Alpha
References
Allouche, J.-P. and Shallit, J. "The Ring of
-Regular Sequences." Theoret. Comput. Sci. 98,
16-197, 1992.Referenced on Wolfram|Alpha
Regular SequenceCite this as:
Weisstein, Eric W. "Regular Sequence." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/RegularSequence.html