|
|
A208633
|
|
Number of n X 4 0..1 arrays with new values 0..1 introduced in row major order and no element equal to more than one of its immediate leftward or upward or right-upward antidiagonal neighbors.
|
|
1
|
|
|
8, 23, 71, 225, 722, 2331, 7548, 24476, 79423, 257807, 836973, 2717446, 8823199, 28648292, 93019712, 302032007, 980690055, 3184277945, 10339281402, 33571429395, 109005736508, 353939387572, 1149233948207, 3731539152111
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
|
|
LINKS
|
|
|
FORMULA
|
Empirical: a(n) = 5*a(n-1) - 6*a(n-2) + a(n-3).
Empirical g.f.: x*(8 - 17*x + 4*x^2) / (1 - 5*x + 6*x^2 - x^3). - Colin Barker, Jul 05 2018
|
|
EXAMPLE
|
Some solutions for n=4:
..0..0..1..0....0..0..0..0....0..0..1..0....0..0..1..0....0..1..0..1
..1..0..1..0....1..1..1..0....1..0..1..1....1..0..1..0....1..0..1..0
..0..1..0..1....0..0..1..1....0..1..0..1....1..0..1..0....0..1..0..1
..1..0..1..0....1..0..0..1....0..1..0..0....1..0..1..1....0..1..0..1
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|