A185819 1/5 the number of nX3 0..4 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors.

1, 76, 1584, 49036, 1266624, 35446376, 956312244, 26231137608, 714107480512, 19507209473948, 532049001583280, 14521612514267224, 396222067735245796, 10812492512879834968, 295042237941175359056, 8051107927651445871340

Offset: 1

Author

R. H. Hardin Feb 05 2011

Keywords

• nonn

Comments

Column 3 of A185825

Examples

			Some solutions for 4X3 with a(1,1)=0
..0..1..1....0..3..3....0..3..1....0..0..1....0..2..3....0..0..2....0..0..2
..0..1..0....0..4..3....0..3..1....0..1..1....0..2..3....0..2..2....4..4..2
..0..0..0....4..4..2....0..2..2....2..1..3....0..2..4....4..4..4....1..4..4
..1..1..1....4..2..2....1..1..2....2..1..3....0..2..4....1..1..1....1..1..1
		

Links

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

Formula

Empirical: a(n)=17*a(n-1)+327*a(n-2)-1020*a(n-3)-6773*a(n-4)+2794*a(n-5)+32525*a(n-6)+131655*a(n-7)-337771*a(n-8)+33788*a(n-9)+517885*a(n-10)-1145646*a(n-11)-5007180*a(n-12)+7715688*a(n-13)[phone]*a(n-14)-82942336*a(n-15)-35554304*a(n-16)[phone]*a(n-17)[phone]*a(n-18)-172261376*a(n-19)-774750208*a(n-20)-958660608*a(n-21)-1396703232*a(n-22)-1811939328*a(n-23)