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A243639 Number of length n+2 0..8 arrays with no three unequal elements in a row and new values 0..8 introduced in 0..8 order.

%I A243639 #6 Jul 23 2025 11:21:23
%S A243639 4,9,21,51,127,324,844,2243,6073,16737,46905,133556,386062,1132107,
%T A243639 3365627,10137558,30920924,95456942,298125982,941555265,3005897555,
%U A243639 9696696210,31596681866,103963289341,345299662267,1157307776719
%N A243639 Number of length n+2 0..8 arrays with no three unequal elements in a row and new values 0..8 introduced in 0..8 order.
%C A243639 Column 8 of A243641
%H A243639 R. H. Hardin, <a href="/A243639/b243639.txt">Table of n, a(n) for n = 1..210</a>
%F A243639 Empirical: a(n) = 15*a(n-1) -76*a(n-2) +78*a(n-3) +554*a(n-4) -1518*a(n-5) -1000*a(n-6) +6492*a(n-7) -505*a(n-8) -13105*a(n-9) +2036*a(n-10) +13670*a(n-11) +672*a(n-12) -5632*a(n-13) -1680*a(n-14)
%e A243639 Some solutions for n=5
%e A243639 ..0....0....0....0....0....0....0....0....0....0....0....0....0....0....0....0
%e A243639 ..0....1....1....1....0....0....1....1....1....0....1....1....1....0....1....1
%e A243639 ..1....1....1....1....1....1....1....1....0....0....0....0....0....0....0....1
%e A243639 ..0....1....2....0....1....1....0....1....1....0....0....0....0....1....0....1
%e A243639 ..0....2....1....0....2....1....0....1....1....0....1....2....0....1....0....0
%e A243639 ..1....2....1....0....2....2....1....1....1....1....1....2....2....2....2....0
%e A243639 ..0....2....2....2....3....2....1....2....0....0....2....1....2....1....0....1
%K A243639 nonn
%O A243639 1,1
%A A243639 _R. H. Hardin_, Jun 08 2014