login
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
1, 196, 7854, 546280, 28967421, 1748982326, 98953708266, 5781843976125, 332434487651623, 19267808077145684, 1112287426359828719, 64338491237732078416, 3717840477156798616939, 214944959102538319886245
OFFSET
1,2
COMMENTS
Column 3 of A185903
LINKS
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
KEYWORD
nonn
AUTHOR
R. H. Hardin Feb 06 2011
STATUS
approved