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

1,2

Comments

Column 3 of A185903

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)+974325088*a(n-10)-1138247283*a(n-11)-3413532399*a(n-12)-6260334885*a(n-13)+43564745112*a(n-14)+67448015978*a(n-15)-317297809157*a(n-16)+933625841547*a(n-17)+1754321298765*a(n-18)-4758109448687*a(n-19)-10555269100243*a(n-20)-10151918327418*a(n-21)-9040337868996*a(n-22)-20928026247912*a(n-23)

Example

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

Crossrefs

Sequence in context: A061622 A128990 A061619 * A285922 A285858 A203540

Adjacent sequences: A185897 A185898 A185899 * A185901 A185902 A185903

Keyword

nonn

Author

R. H. Hardin Feb 06 2011

Status

approved