A206652 - OEIS

%I #5 Mar 31 2012 12:37:12

%S 102,390,1517,5805,22346,86251,332419,1281181,4939106,19039804,

%T 73394261,282923766,1090629910,4204204919,16206551390,62473746310,

%U 240826563663,928348880740,3578640462085,13795101927045,53177970281187

%N Number of (n+2)X3 0..1 arrays with every 3X3 subblock having three equal elements in a row horizontally, vertically or nw-to-se diagonally exactly two ways, and new values 0..1 introduced in row major order

%C Column 1 of A206659

%H R. H. Hardin, <a href="/A206652/b206652.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 5*a(n-2) +26*a(n-3) +42*a(n-4) +33*a(n-5) -28*a(n-6) -100*a(n-7) -102*a(n-8) -100*a(n-9) -122*a(n-10) -266*a(n-11) -194*a(n-12) -25*a(n-13) +279*a(n-14) +129*a(n-15) -147*a(n-16) -429*a(n-17) -379*a(n-18) -594*a(n-19) -576*a(n-20) -396*a(n-21) +452*a(n-22) +1179*a(n-23) +660*a(n-24) +391*a(n-25) -322*a(n-26) -54*a(n-27) +90*a(n-28)

%e Some solutions for n=4

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

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

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

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

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

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

%K nonn

%O 1,1

%A _R. H. Hardin_ Feb 11 2012