A237915 - OEIS

%I #5 Feb 15 2014 17:25:13

%S 256,1584,9892,63476,406468,2591160,16574240,105734776,676470380,

%T 4314907116,27605297244,176086915376,1126539110360,7185841737072,

%U 45972584759476,293245625954804,1876081040647348,11966954890116312

%N Number of (n+1)X(1+1) 0..3 arrays with the upper median plus the lower median of every 2X2 subblock differing from its horizontal and vertical neighbors by exactly one

%C Column 1 of A237921

%H R. H. Hardin, <a href="/A237915/b237915.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 9*a(n-2) +1028*a(n-4) +10373*a(n-6) +27367*a(n-8) -32996*a(n-10) -169776*a(n-12) -127168*a(n-14) +64512*a(n-16) +589824*a(n-18)

%e Some solutions for n=4

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

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

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

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

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

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 15 2014