%I #18 Dec 14 2021 21:43:45
%S 1,2,7,57,182,3124,1068,32318,390624,280182,3626068,23157318,
%T 120813568,1220703124,1097376068,11109655182,49925501068,762939453124,
%U 355101282318,19073486328124,15613890344818,365855836217682,2384185791015624
%N Minimum m coprime to 5 such that the convergence speed of m^^m := m^(m^^(m-1)) is equal to n >= 0, where A317905(n) represents the convergence speed of m^^m (and m = A047201(n), the n-th non-multiple of 5).
%C Let "s" denote the last digit of m, and V(m(s)) its convergence speed. For any n, the smallest bases that are not congruent to 5 modulo 10 (as in A337392) cannot be such that s = 6, since V(m(6)) = V(m(4)) + 2.
%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, 2020, 26(3), 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.
%e For n = 19, a(19) = 19073486328124 is the smallest base (radix-10) of the tetration m^^m which is characterized by a congruence speed of 19.
%Y Cf. A317824, A317903, A317905, A321130, A337392.
%K nonn,base
%O 0,2
%A _Marco Ripà_, Sep 24 2020