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%I #23 Aug 23 2022 09:54:21
%S 0,1,5,7,15,18,24
%N Values of m (mod 25) such that V(m) >= 2, where V(m) indicates the constant convergence speed of the tetration base m.
%C This sequence represents the values of the base a such that a^^m, where ^^ indicates tetration or hyper-4 (e.g., 3^^4=3^(3^(3^3))), is characterized by a convergence speed at or above 2 (fast m-adic convergence). Only 26% of the positive integers belong to this list (see A317905).
%D Marco Ripà, La strana coda della serie n^n^...^n, Trento, UNI Service, Nov 2011. ISBN 978-88-6178-789-6
%H Marco Ripà, <a href="https://doi.org/10.7546/nntdm.2020.26.3.245-260">On the constant congruence speed of tetration</a>, Notes on Number Theory and Discrete Mathematics, Volume 26, 2020, Number 3, pp. 245—260.
%H Marco Ripà, <a href="https://doi.org/10.7546/nntdm.2021.27.4.43-61">The congruence speed formula</a>, Notes on Number Theory and Discrete Mathematics, 2021, 27(4), 43-61.
%H Marco Ripà and Luca Onnis, <a href="https://doi.org/10.7546/nntdm.2022.28.3.441-457">Number of stable digits of any integer tetration</a>, Notes on Number Theory and Discrete Mathematics, 2022, 28(3), 441-457.
%H Wikipedia, <a href="https://en.wikipedia.org/wiki/Tetration">Tetration</a>
%F For m = 57, m (mod 25) == 7 and 7^^n has a convergence speed greater than 1, since A317905(m = 57) = 3 > 1 and also A317905(m = 7) = 2 > 1.
%Y Cf. A067251, A317824, A317903, A317905, A321131.
%K nonn,fini,full
%O 1,3
%A _Marco Ripà_, Oct 27 2018
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