A237632 - OEIS

%I #8 Oct 24 2018 06:02:19

%S 702,1220,1310,1488,2086,2900,4132,5720,8248,11504,16546,22928,33024,

%T 46016,66184,91712,132096,184064,264736,366848,528384,736256,1058944,

%U 1467392,2113536,2945024,4235776,5869568,8454144,11780096,16943104

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

%H R. H. Hardin, <a href="/A237632/b237632.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 4*a(n-4) for n>13.

%F Empirical g.f.: 2*x*(351 + 610*x + 655*x^2 + 744*x^3 - 361*x^4 - 990*x^5 - 554*x^6 - 116*x^7 - 48*x^8 - 48*x^9 + 9*x^10 + 24*x^11 + 16*x^12) / ((1 - 2*x^2)*(1 + 2*x^2)). - _Colin Barker_, Oct 24 2018

%e Some solutions for n=5:

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

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

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

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

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

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

%Y Column 3 of A237637.

%K nonn

%O 1,1

%A _R. H. Hardin_, Feb 10 2014