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%I #7 May 04 2021 15:45:22
%S 1,5,19,63,196,588,1731,5049,14689,42809,125364,369678,1099339,
%T 3300091,10006487,30658799,94932890,297079702,939477265,3001846219,
%U 9689289277,31586215805,103968208826,345457027212,1158435912189,3919502591649
%N Number of nonnegative integer arrays of length n+3 with new values 0 upwards introduced in order, no three adjacent elements all unequal, and containing the value 2.
%C Column 1 of A211849.
%H R. H. Hardin, <a href="/A211842/b211842.txt">Table of n, a(n) for n = 1..210</a>
%e Some solutions for n=3
%e ..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
%e ..1....1....1....1....0....1....0....1....0....1....1....1....0....1....0....1
%e ..1....1....1....1....1....0....1....1....1....0....1....1....0....0....1....1
%e ..1....1....1....2....1....0....0....0....1....1....2....2....1....0....1....2
%e ..2....1....2....2....2....0....0....0....2....1....1....2....1....2....1....2
%e ..2....2....1....3....2....2....2....2....1....2....2....1....2....2....2....2
%Y Cf. A211849.
%K nonn
%O 1,2
%A _R. H. Hardin_ Apr 22 2012
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