|
|
A230179
|
|
Number of n X 3 0..2 arrays x(i,j) with each element horizontally or antidiagonally next to at least one element with value 2-x(i,j).
|
|
1
|
|
|
3, 27, 231, 1971, 16815, 143451, 1223799, 10440387, 89068287, 759853035, 6482404167, 55302225363, 471790411599, 4024904802939, 34336981580055, 292933215008739, 2499051008758431, 21319726218790923, 181881331934084583
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
FORMULA
|
Empirical: a(n) = 9*a(n-1) - 4*a(n-2).
G.f.: 3*x / (1 - 9*x + 4*x^2).
a(n) = ((-3)*(2^(-n)*((9-sqrt(65))^n - (9+sqrt(65))^n))) / sqrt(65).
(End)
|
|
EXAMPLE
|
Some solutions for n=3:
..0..2..0....0..2..1....2..0..2....2..0..2....1..1..1....1..1..1....1..1..1
..0..0..2....0..1..2....2..0..0....2..1..1....1..0..2....1..0..2....2..0..0
..2..2..0....2..0..2....2..2..0....1..2..0....2..2..0....0..2..0....0..2..0
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|