A203791 - OEIS

%I #8 Jun 05 2018 08:18:53

%S 5488,142192,3784288,101071600,2700695728,72168659104,1928524187248,

%T 51534966781936,1377142783787488,36800688925407472,983406168592794928,

%U 26279064902536667680,702242139855909029488,18765660986075071030384

%N Number of (n+1) X 4 0..3 arrays with every 2 X 2 subblock having equal diagonal elements or equal antidiagonal elements.

%C Column 3 of A203796.

%H R. H. Hardin, <a href="/A203791/b203791.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 31*a(n-1) -117*a(n-2) +72*a(n-3).

%F Empirical g.f.: 16*x*(343 - 1746*x + 1152*x^2) / (1 - 31*x + 117*x^2 - 72*x^3). - _Colin Barker_, Jun 05 2018

%e Some solutions for n=4:

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

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

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

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

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

%Y Cf. A203796.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jan 05 2012