A268369 Number of 3 X n arrays containing n copies of 0..3-1 with row sums equal.

0, 12, 216, 2700, 54000, 1054200, 20991600, 445365900, 9628264800, 212635396512, 4790810344320, 109495671909624, 2534856710978592, 59336480231336880, 1402136110916757216, 33409975384414912140, 801962422581013417152

Offset: 1

Author

R. H. Hardin, Feb 03 2016

Keywords

• nonn

Comments

Row 3 of A268367.

Examples

			Some solutions for n=5
..1..1..1..0..2....0..0..2..2..1....1..0..2..1..1....0..1..2..0..2
..0..1..0..2..2....1..1..1..2..0....1..0..2..0..2....0..1..1..1..2
..0..0..2..2..1....0..1..2..0..2....0..0..2..1..2....2..0..0..1..2
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..40

Crossrefs

Cf. A268367.

Formula

Conjecture: n^4*(1057*n^2 -3473*n +2902)*a(n) -(n-1) *(14798*n^5 -63420*n^4 +104199*n^3 -81821*n^2 +31698*n -4968)*a(n-1) +(-235711*n^6 +1717323*n^5 -5084885*n^4 +7773081*n^3 -6422772*n^2 +2716308*n -472176)*a(n-2) -96*(6*n -11) *(6*n-13) *(1057*n^2-1359*n+486) *(n-2)^2*a(n-3)=0. - R. J. Mathar, Feb 18 2016