A206688 Number of nX4 0..3 arrays with no element equal to another within two positions in the same row or column, and new values 0..3 introduced in row major order.

2, 36, 176, 916, 4704, 24492, 127008, 660888, 3436488, 17884080, 93059016, 484334480, 2520695968, 13119605656, 68284077520, 355405952496, 1849822022856, 9628019156288, 50112266984832, 260826450827576, 1357560738338768

Offset: 1

Author

R. H. Hardin Feb 11 2012

Keywords

• nonn

Comments

Column 4 of A206692

Examples

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

Links

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

Formula

Empirical: a(n) = 8*a(n-1) -8*a(n-2) -48*a(n-3) +48*a(n-4) +140*a(n-5) +67*a(n-6) -968*a(n-7) +1564*a(n-8) -586*a(n-9) -1008*a(n-10) -32*a(n-11) +1304*a(n-12) +80*a(n-13) -512*a(n-14) for n>15