|
|
A222684
|
|
Number of nX2 0..2 arrays with exactly floor(nX2/2) elements unequal to at least one horizontal or antidiagonal neighbor, with new values introduced in row major 0..2 order
|
|
1
|
|
|
0, 3, 8, 50, 216, 1120, 5440, 27576, 138560, 704880, 3590400, 18382208, 94348800, 485706240, 2505943040, 12956458880, 67108497408, 348156924160, 1808830924800, 9409953735168, 49010429163520, 255537995550720, 1333668320575488
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
COMMENTS
|
|
|
LINKS
|
|
|
FORMULA
|
Empirical: 3*(n-1)*n*(49*n-73)*a(n) = 5*(n-1)*(98*n^2-195*n+91)*a(n-1) + 5*(7*n-5)*(49*n^2-136*n+96)*a(n-2) - 8*(n-1)*(2*n-5)*(49*n-24)*a(n-3)
a(n) ~ 16^n/(3^n*sqrt(21*Pi*n)). (End)
|
|
EXAMPLE
|
All solutions for n=3
..0..0....0..0....0..0....0..0....0..0....0..1....0..0....0..1
..1..2....0..0....1..0....0..0....0..1....2..2....0..1....0..0
..2..2....1..2....0..0....1..0....0..0....2..2....2..2....0..0
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|