|
|
A183981
|
|
1/4 the number of (n+1) X 5 binary arrays with all 2 X 2 subblock sums the same.
|
|
1
|
|
|
15, 17, 20, 26, 36, 56, 92, 164, 300, 572, 1100, 2156, 4236, 8396, 16652, 33164, 66060, 131852, 263180, 525836, 1050636, 2100236, 4198412, 8394764, 16785420, 33566732, 67125260, 134242316, 268468236, 536920076, 1073807372, 2147581964, 4295098380
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
|
|
LINKS
|
|
|
FORMULA
|
Empirical: a(n) = 3*a(n-1) - 6*a(n-3) + 4*a(n-4).
G.f.: x*(15 - 28*x - 31*x^2 + 56*x^3) / ((1 - x)*(1 - 2*x)*(1 - 2*x^2)).
a(n) = 3*2^(n/2-1) + 2^(n-1) + 12 for n even.
a(n) = 2^(n-1) + 2^((n+1)/2) + 12 for n odd.
(End)
|
|
EXAMPLE
|
Some solutions for 7 X 5:
..0..1..0..1..0....0..0..0..0..1....0..1..0..1..0....0..1..0..1..0
..1..1..1..1..1....1..0..1..0..0....0..1..0..1..0....0..0..0..0..0
..0..1..0..1..0....0..0..0..0..1....1..0..1..0..1....1..0..1..0..1
..1..1..1..1..1....1..0..1..0..0....1..0..1..0..1....0..0..0..0..0
..1..0..1..0..1....0..0..0..0..1....0..1..0..1..0....1..0..1..0..1
..1..1..1..1..1....1..0..1..0..0....0..1..0..1..0....0..0..0..0..0
..1..0..1..0..1....0..0..0..0..1....1..0..1..0..1....1..0..1..0..1
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|