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A208404 Number of n X 4 0..3 arrays with new values 0..3 introduced in row major order and no element equal to more than two of its immediate leftward or upward or right-upward antidiagonal neighbors.

%I A208404 #8 Jul 02 2018 14:14:19
%S A208404 15,2698,658450,163422914,40595679634,10084768380770,2505261257850802,
%T A208404 622357842865595522,154606345205565641170,38407360426219085921186,
%U A208404 9541169432411414821885426,2370220528768971149166621890
%N A208404 Number of n X 4 0..3 arrays with new values 0..3 introduced in row major order and no element equal to more than two of its immediate leftward or upward or right-upward antidiagonal neighbors.
%C A208404 Column 4 of A208408.
%H A208404 R. H. Hardin, <a href="/A208404/b208404.txt">Table of n, a(n) for n = 1..210</a>
%F A208404 Empirical: a(n) = 262*a(n-1) - 3385*a(n-2) + 2868*a(n-3) - 576*a(n-4) for n>5.
%F A208404 Empirical g.f.: x*(15 - 1232*x + 2349*x^2 - 1276*x^3 + 192*x^4) / ((1 - 13*x + 4*x^2)*(1 - 249*x + 144*x^2)). - _Colin Barker_, Jul 02 2018
%e A208404 Some solutions for n=4
%e A208404 ..0..0..1..2....0..1..0..0....0..0..0..1....0..1..1..1....0..0..0..1
%e A208404 ..0..3..3..0....2..0..3..0....1..2..1..1....0..0..0..1....1..0..1..1
%e A208404 ..1..0..1..2....2..0..3..1....0..2..0..3....0..1..0..0....2..2..1..0
%e A208404 ..1..1..0..0....1..2..0..2....0..0..2..1....0..1..1..1....0..3..0..0
%Y A208404 Cf. A208408.
%K A208404 nonn
%O A208404 1,1
%A A208404 _R. H. Hardin_, Feb 26 2012