A183519 Number of nX2 0..2 arrays with each element equal to either the sum mod 3 of its horizontal and vertical neighbors or the sum mod 3 of its diagonal and antidiagonal neighbors.

3, 9, 31, 95, 309, 911, 2803, 8673, 26619, 81959, 252477, 777327, 2393627, 7371657, 22698115, 69895583, 215235669, 662786215, 2040959827, 6284869089, 19353386043, 59596135287, 183518286189, 565119695167, 1740209766219, 5358741068409

Offset: 1

Author

R. H. Hardin Jan 05 2011

Keywords

• nonn

Comments

Column 2 of A183526

Examples

			Some solutions for 3X2
..1..2....0..2....2..1....2..0....0..2....2..2....1..0....1..0....0..1....1..2
..0..1....1..2....1..2....0..2....1..2....0..0....1..2....1..2....2..1....2..1
..1..2....2..1....0..2....0..0....0..2....1..1....1..0....2..1....1..2....2..0
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n)=3*a(n-1)+6*a(n-3)-16*a(n-4)+7*a(n-6)-25*a(n-7)-44*a(n-9)+102*a(n-10)-184*a(n-12)+520*a(n-13)+320*a(n-15)-720*a(n-16)+640*a(n-18)-1600*a(n-19)