A281471 - OEIS

%I #8 Feb 19 2019 15:16:26

%S 4,25,24,39,57,87,145,241,397,669,1133,1909,3229,5477,9277,15717,

%T 26653,45189,76605,129893,220253,373445,633213,1073701,1820573,

%U 3086981,5234365,8875493,15049437,25518149,43269117,73367973,124404253,210942469

%N Number of 3 X n 0..1 arrays with no element equal to more than two of its horizontal, diagonal or antidiagonal neighbors and with new values introduced in order 0 sequentially upwards.

%H R. H. Hardin, <a href="/A281471/b281471.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 2*a(n-1) - a(n-2) + 2*a(n-3) - 2*a(n-4) for n>8.

%F Empirical g.f.: x*(4 + 17*x - 22*x^2 + 8*x^3 - 39*x^4 + 14*x^5 - 2*x^6 + 2*x^7) / ((1 - x)*(1 - x - 2*x^3)). - _Colin Barker_, Feb 19 2019

%e Some solutions for n=4:

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

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

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

%Y Row 3 of A281469.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jan 22 2017