|
| |
|
|
A209376
|
|
1/4 the number of (n+1) X 3 0..2 arrays with every 2 X 2 subblock having distinct edge sums.
|
|
1
|
|
|
|
8, 17, 34, 80, 170, 410, 882, 2138, 4610, 11186, 24130, 58562, 126338, 306626, 661506, 1605506, 3463682, 8406530, 18136066, 44017154, 94961666, 230476802, 497225730, 1206792194, 2603507714, 6318845954, 13632143362, 33085906946, 71378829314
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,1
|
|
|
COMMENTS
|
|
|
|
LINKS
|
|
|
|
FORMULA
|
Empirical: a(n) = a(n-1) + 6*a(n-2) - 6*a(n-3) - 4*a(n-4) + 4*a(n-5).
Empirical g.f.: x*(8 + 9*x - 31*x^2 - 8*x^3 + 20*x^4) / ((1 - x)*(1 - 6*x^2 + 4*x^4)). - Colin Barker, Jul 09 2018
|
|
|
EXAMPLE
|
Some solutions for n=4:
..1..2..2....2..1..2....1..0..1....0..1..0....0..0..2....0..2..2....2..1..2
..0..0..1....2..0..2....2..0..2....2..2..0....2..1..2....0..1..0....2..0..0
..1..2..2....1..0..1....1..0..1....0..1..0....0..0..2....0..2..2....2..1..2
..0..0..1....2..2..2....2..0..2....0..2..2....2..1..2....0..1..0....0..0..2
..1..2..2....0..1..0....2..1..2....0..1..0....2..0..2....2..2..2....2..1..2
|
|
|
CROSSREFS
|
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
|
|
|
STATUS
|
approved
|
| |
|
|
