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%I #17 Jan 08 2024 16:47:32
%S 1,2,3,5,5,7,9,12,16,21,28,37,45,58,73,93,101,124,150,179,216,257,309,
%T 376,453,551,662,798,957,1149,1371,1647,1977,2382,2871,3450,4160,4995,
%U 5991,7190,8631,10370,12462,14991,17983,21608,25947,31157,37406,44921,53921
%N Number of quaternary steady words of length n (with respect to the permutations of symbols).
%C A squarefree word is steady if it remains squarefree after deletion of any single letter.
%H Martin Ehrenstein, <a href="/A357250/b357250.txt">Table of n, a(n) for n = 3..100</a>
%H Michał Dębski, Jarosław Grytczuk, and Bartłomiej Pawlik, <a href="https://arxiv.org/abs/2209.08507">Extensions and reductions of square-free words</a>, arXiv:2209.08507 [math.CO], 2022. See Table 1 p. 3.
%H Michał Dębski, Jarosław Grytczuk, and Bartłomiej Pawlik, <a href="https://doi.org/10.1016/j.disc.2023.113825">Extensions and reductions of squarefree words</a>, Discrete Math. 347 (2024), 113825.
%K nonn
%O 3,2
%A _Michel Marcus_, Sep 20 2022
%E a(33)-a(51) from _Martin Ehrenstein_, Sep 22 2022