|
|
A237227
|
|
Number of (n+1) X (1+1) 0..2 arrays with the maximum plus the minimum of every 2 X 2 subblock differing from its horizontal and vertical neighbors by exactly one.
|
|
1
|
|
|
81, 268, 928, 2784, 9628, 28912, 100008, 300256, 1038560, 3118208, 10785696, 32383104, 112011072, 336303872, 1163253760, 3492571136, 12080581376, 36270926848, 125458829824, 376679553024, 1302910621696, 3911879237632
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
FORMULA
|
Empirical: a(n) = 8*a(n-2) + 24*a(n-4) + 8*a(n-6) for n>7.
Empirical g.f.: x*(81 + 268*x + 280*x^2 + 640*x^3 + 260*x^4 + 208*x^5 + 64*x^6) / ((1 + 2*x^2)*(1 - 10*x^2 - 4*x^4)). - Colin Barker, Oct 21 2018
|
|
EXAMPLE
|
Some solutions for n=5:
..2..1....1..2....0..2....1..0....0..2....2..1....2..0....1..0....2..1....2..1
..0..0....0..0....1..0....2..1....0..0....2..2....0..1....1..0....1..0....0..0
..1..0....1..0....0..1....1..1....1..0....0..1....0..0....2..1....1..1....1..0
..2..2....2..2....2..2....1..1....1..2....0..1....2..2....1..2....1..1....2..2
..1..1....1..2....1..1....2..2....1..1....1..2....1..2....0..1....0..0....1..2
..0..2....1..0....1..1....0..0....0..2....2..1....2..0....0..1....0..2....0..0
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|