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A233728 Number of (n+1)X(3+1) 0..3 arrays with every 2X2 subblock having the sum of the absolute values of the edge differences equal to 6 and no adjacent elements equal.

%I A233728 #6 Jul 23 2025 08:10:25
%S A233728 556,3972,29816,233432,1851404,14802604,118695412,953471940,
%T A233728 7663964828,61629254552,495650497344,3986689001988,32067041076200,
%U A233728 257939925202452,2074814466960036,16689518674136900,134248084171273808
%N A233728 Number of (n+1)X(3+1) 0..3 arrays with every 2X2 subblock having the sum of the absolute values of the edge differences equal to 6 and no adjacent elements equal.
%C A233728 Column 3 of A233733
%H A233728 R. H. Hardin, <a href="/A233728/b233728.txt">Table of n, a(n) for n = 1..210</a>
%F A233728 Empirical: a(n) = 9*a(n-1) +46*a(n-2) -508*a(n-3) -481*a(n-4) +10680*a(n-5) -3945*a(n-6) -112548*a(n-7) +115263*a(n-8) +657688*a(n-9) -958275*a(n-10) -2192200*a(n-11) +4058993*a(n-12) +4067658*a(n-13) -9776097*a(n-14) -3651898*a(n-15) +13759514*a(n-16) +407041*a(n-17) -11221093*a(n-18) +1862871*a(n-19) +5154086*a(n-20) -1437504*a(n-21) -1269561*a(n-22) +444011*a(n-23) +147392*a(n-24) -60418*a(n-25) -4972*a(n-26) +2810*a(n-27) -123*a(n-28)
%e A233728 Some solutions for n=3
%e A233728 ..3..2..0..3....1..3..1..0....3..2..3..1....1..3..1..3....0..1..0..1
%e A233728 ..2..0..1..2....3..2..0..2....1..3..1..0....0..1..0..2....1..3..1..3
%e A233728 ..3..1..3..1....0..1..2..3....0..2..3..2....2..3..2..1....0..2..0..2
%e A233728 ..1..2..1..2....3..2..0..2....1..0..1..0....0..1..3..0....1..0..1..0
%K A233728 nonn
%O A233728 1,1
%A A233728 _R. H. Hardin_, Dec 15 2013