login
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.
1

%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