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%I #7 Mar 09 2023 17:27:53
%S 3,11,40,158,684,3232,16533,90862,533013,3319374,21844874,151329961,
%T 1099822975,8361244270,66320787389,547602710173,4697109624463,
%U 41777867546600,384671271459042,3661037447467530,35965775221739498
%N Number of length n+2 0..n arrays with no three equal elements in a row and new values 0..n introduced in 0..n order.
%C Diagonal of A242472.
%H R. H. Hardin, <a href="/A242467/b242467.txt">Table of n, a(n) for n = 1..163</a>
%e Some solutions for n=4
%e ..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
%e ..1....1....1....0....0....1....1....1....1....0....1....1....1....1....1....1
%e ..0....2....0....1....1....1....2....2....2....1....0....2....1....1....0....2
%e ..2....1....1....2....2....2....1....0....0....1....2....0....0....0....1....3
%e ..2....1....0....0....2....0....0....0....1....2....1....0....0....0....2....2
%e ..3....2....1....0....3....2....0....1....2....1....2....3....2....1....0....1
%Y Cf. A242472.
%K nonn
%O 1,1
%A _R. H. Hardin_, May 15 2014