A203651 - OEIS

%I #9 Jun 04 2018 12:20:28

%S 729,28057,1116249,44577561,1780968921,71156938905,2843024036697,

%T 113591039131161,4538450923550937,181330649884558233,

%U 7244939996157320793,289466538539290446105,11565434217440894223321,462088880162456091840153

%N 1/25 the number of (n+1) X 4 0..4 arrays with every 2 X 2 subblock having equal diagonal elements or equal antidiagonal elements.

%C Column 3 of A203656.

%H R. H. Hardin, <a href="/A203651/b203651.txt">Table of n, a(n) for n = 1..210</a>

%F Empirical: a(n) = 45*a(n-1) -204*a(n-2) +96*a(n-3).

%F Empirical g.f.: x*(729 - 4748*x + 2400*x^2) / (1 - 45*x + 204*x^2 - 96*x^3). - _Colin Barker_, Jun 04 2018

%e Some solutions for n=4:

%e ..4..1..0..1....2..0..1..4....3..0..4..4....4..3..4..4....2..4..3..3

%e ..1..0..4..0....3..2..0..1....2..3..0..4....0..4..0..4....2..2..4..3

%e ..3..1..0..4....0..3..2..0....4..2..3..0....0..0..1..0....1..2..2..4

%e ..0..3..1..0....1..0..3..2....0..4..2..3....2..0..0..4....2..2..2..2

%e ..0..0..3..1....4..1..0..3....0..0..4..2....2..2..0..0....4..2..1..2

%Y Cf. A203656.

%K nonn

%O 1,1

%A _R. H. Hardin_, Jan 04 2012