|
|
A218236
|
|
Hilltop maps: number of n X 2 binary arrays indicating the locations of corresponding elements not exceeded by any king-move neighbor in a random 0..3 n X 2 array.
|
|
2
|
|
|
3, 15, 63, 255, 1017, 4065, 16257, 65025, 260091, 1040319, 4161087, 16643583, 66571281, 266272929, 1065042945, 4259976705, 17039126547, 68153385231, 272601057663, 1090354299903, 4361217485769, 17444071124289, 69773089368321
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
|
|
LINKS
|
|
|
FORMULA
|
Empirical: a(n) = 3*a(n-1) + 3*a(n-2) + 3*a(n-3) + 3*a(n-4) + 3*a(n-5) + 3*a(n-6) + 3*a(n-7).
Empirical g.f.: 3*x*(1 + x)^2*(1 + x^2)^2 / (1 - 3*x - 3*x^2 - 3*x^3 - 3*x^4 - 3*x^5 - 3*x^6 - 3*x^7). - Colin Barker, Mar 10 2018
|
|
EXAMPLE
|
Some solutions for n=3:
..1..0....1..1....0..1....0..1....1..1....1..0....0..0....0..1....1..0....1..1
..0..1....0..1....1..0....1..1....1..1....1..0....0..0....1..1....1..0....0..0
..1..0....1..0....0..1....0..0....0..0....1..0....1..0....1..1....0..0....0..1
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|