A203651 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.

729, 28057, 1116249, 44577561, 1780968921, 71156938905, 2843024036697, 113591039131161, 4538450923550937, 181330649884558233, 7244939996157320793, 289466538539290446105, 11565434217440894223321, 462088880162456091840153

Offset: 1

Author

R. H. Hardin, Jan 04 2012

Keywords

• nonn

Comments

Column 3 of A203656.

Examples

			Some solutions for n=4:
..4..1..0..1....2..0..1..4....3..0..4..4....4..3..4..4....2..4..3..3
..1..0..4..0....3..2..0..1....2..3..0..4....0..4..0..4....2..2..4..3
..3..1..0..4....0..3..2..0....4..2..3..0....0..0..1..0....1..2..2..4
..0..3..1..0....1..0..3..2....0..4..2..3....2..0..0..4....2..2..2..2
..0..0..3..1....4..1..0..3....0..0..4..2....2..2..0..0....4..2..1..2
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..210

Crossrefs

Cf. A203656.

Formula

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

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