A204391 - OEIS

%I #9 Jun 07 2018 11:47:20

%S 144,648,2952,13448,61336,279752,1276088,5820872,26552184,121119048,

%T 552490872,2520216008,11496098296,52440058952,239208098168,

%U 1091160371912,4977385663224,22704607570248,103568266524792,472432117479368

%N Number of (n+2) X 3 0..1 arrays with no 3 X 3 subblock having three equal diagonal elements or three equal antidiagonal elements, and new values 0..1 introduced in row major order.

%C Column 1 of A204398.

%H R. H. Hardin, <a href="/A204391/b204391.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 5*a(n-1) - 10*a(n-3) + 4*a(n-4).

%F Empirical g.f.: 8*x*(18 - 9*x - 36*x^2 + 16*x^3) / ((1 - 5*x + 2*x^2)*(1 - 2*x^2)). - _Colin Barker_, Jun 07 2018

%e Some solutions for n=3:

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

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

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

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

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

%Y Cf. A204398.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jan 15 2012