A253463 - OEIS

%I #10 Dec 14 2018 06:07:41

%S 540,800,1400,3072,8536,15888,44464,94416,273808,562320,1622320,

%T 3376272,9768496,20246928,58535344,121496976,351356848,728945040,

%U 2107845040,4373737872,12647655856,26242285968,75884757424,157453992336

%N Number of (n+1) X (2+1) 0..2 arrays with every 2 X 2 subblock diagonal maximum minus antidiagonal minimum unequal to its neighbors horizontally, vertically, diagonally and antidiagonally.

%H R. H. Hardin, <a href="/A253463/b253463.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 5*a(n-2) + 8*a(n-4) - 12*a(n-6) for n>7.

%F Empirical g.f.: 4*x*(135 + 200*x - 325*x^2 - 232*x^3 - 696*x^4 - 1468*x^5 - 734*x^6) / ((1 - x)*(1 + x)*(1 + 2*x^2)*(1 - 6*x^2)). - _Colin Barker_, Dec 14 2018

%e Some solutions for n=4:

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

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

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

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

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

%Y Column 2 of A253468.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jan 01 2015