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 A208195 Number of n X 2 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 left-upward diagonal neighbors. 1

%I

%S 2,14,178,2653,41272,648569,10215440,160984657,2537249104,39990174809,

%T 630298266416,9934351303777,156578831693200,2467894630281641,

%U 38897365218137072,613075213064694577,9662896575843028048

%N Number of n X 2 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 left-upward diagonal neighbors.

%C Column 2 of A208201.

%H R. H. Hardin, <a href="/A208195/b208195.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 18*a(n-1) - 31*a(n-2) - 66*a(n-3) - 24*a(n-4) for n>5.

%F Empirical g.f.: x*(2 - 22*x - 12*x^2 + 15*x^3 + 8*x^4) / ((1 - 3*x - 2*x^2)*(1 - 15*x - 12*x^2)). - _Colin Barker_, Jun 29 2018

%e Some solutions for n=4:

%e ..0..0....0..0....0..0....0..0....0..0....0..0....0..1....0..0....0..0....0..1

%e ..0..1....1..0....1..1....1..0....1..0....0..1....1..1....0..1....0..1....1..0

%e ..0..0....2..0....0..1....1..0....0..0....0..0....0..0....0..2....1..0....0..0

%e ..1..2....1..2....0..0....0..1....0..1....0..2....0..1....1..3....2..2....2..0

%Y Cf. A208201.

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 24 2012

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Last modified December 7 17:25 EST 2022. Contains 358668 sequences. (Running on oeis4.)