Number Theory


On the Convergence Speed of Tetration

Authors: Marco Ripà

In 2011, in his book “La strana coda della serie n^n^...^n", M. Ripà analyzed some properties involving the rightmost figures of integer tetration, the iterated exponentiation a^^b, characterized by an increasing number of stable digits for any base a > 1. A few conjectures arose about how many new stable digits are generated by any unitary increment of the hyperexponent b, and Ripà indicated this value as V(a) or “convergence speed” of a. In fact, when b is large enough, V(a) seems to not depend from b, taking on a (strictly positive) unique value, and many observations supported this claim. Moreover, we claim that V(a) = 1 for any a(mod 25) congruent to {2, 3, 4, 6, 8, 9, 11, 12, 13, 14, 16, 17, 19, 21, 22, 23} and V(a)>=2 otherwise.

Comments: 4 Pages.

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Submission history

[v1] 2018-10-14 17:11:04
[v2] 2018-10-23 16:14:29

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