A185900 1/8 the number of nX3 0..7 arrays with every element equal to exactly one or two of its horizontal and vertical neighbors.

1, 196, 7854, 546280, 28967421, 1748982326, 98953708266, 5781843976125, 332434487651623, 19267808077145684, 1112287426359828719, 64338491237732078416, 3717840477156798616939, 214944959102538319886245

Offset: 1

Author

R. H. Hardin Feb 06 2011

Keywords

• nonn

Comments

Column 3 of A185903

Examples

			Some solutions for 5X3 with a(1,1)=0
..0..4..0....0..4..0....0..4..4....0..4..0....0..4..0....0..0..0....0..0..0
..0..4..0....0..4..0....0..0..4....0..4..0....0..4..0....4..4..4....0..4..4
..2..4..4....2..2..2....2..2..4....4..6..6....2..2..2....6..0..0....0..2..2
..2..2..0....6..5..6....4..4..4....4..3..5....0..4..6....6..7..7....6..6..6
..0..0..0....6..5..6....2..2..2....4..3..5....0..4..6....6..2..2....2..2..6
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..155

Formula

Empirical: a(n)=32*a(n-1)+1746*a(n-2)-10029*a(n-3)-277751*a(n-4)+323380*a(n-5)+6665171*a(n-6)-1880040*a(n-7)-2212279*a(n-8)-295754815*a(n-9)[phone]*a(n-10)-1138247283*a(n-11)-3413532399*a(n-12)-6260334885*a(n-13)[phone]*a(n-14)[phone]*a(n-15)-317297809157*a(n-16)[phone]*a(n-17)[phone]*a(n-18)-4758109448687*a(n-19)-10555269100243*a(n-20)-10151918327418*a(n-21)-9040337868996*a(n-22)-20928026247912*a(n-23)