[seqfan] Monotonic ordering of nonnegative differences
israel at math.ubc.ca
israel at math.ubc.ca
Thu Oct 10 23:30:58 CEST 2019
There are 52 sequences from A192110 to A192202, contributed by Clark
Kimberling, with Name of the form "Monotonic ordering of nonnegative
differences a^i-b^j, for i>=0, j>=0" for various values of a and b.
>From the Mathematica code, it seems they are all computed by assuming i <=
40. I'm not aware of any theoretical justification for the assumption that
any term in the range of the Data (which might go up to several million)
will arise from i <= 40, although I have no counterexample and it may be
unlikely that there is one. These are related to Catalan's conjecture
(proved by Mihailescu), according to which 1 is not a member of any of
these sequences unless i=1 or j<=1 works. There are also modular reasons
for excluding some values (e.g. if prime p divides b but not a, then all
terms divisible by p are of the form a^i-1). But for many values > 1, I
don't think much is known rigorously.
Should these sequences all get a Comment that the Data are conjectured?
Cheers,
Robert
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