|
|
A217958
|
|
Number of n X 2 arrays of the minimum value of corresponding elements and their horizontal or antidiagonal neighbors in a random 0..2 n X 2 array.
|
|
1
|
|
|
3, 17, 77, 343, 1523, 6761, 30013, 133231, 591427, 2625409, 11654477, 51735495, 229659507, 1019483609, 4525598973, 20089627615, 89180048899, 395879967217, 1757354367693, 7801087777591, 34629879796851, 153725814775369
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
|
|
LINKS
|
|
|
FORMULA
|
Empirical: a(n) = 4*a(n-1) + 2*a(n-2) - a(n-4).
Empirical g.f.: x*(1 + x)*(3 + 2*x + x^2) / (1 - 4*x - 2*x^2 + x^4). - Colin Barker, Jul 23 2018
|
|
EXAMPLE
|
Some solutions for n=3:
..0..0....0..0....2..2....1..0....2..1....1..1....2..2....2..1....2..2....0..0
..0..0....1..2....2..2....0..0....1..0....2..2....2..2....1..1....1..0....0..2
..0..2....1..1....0..0....0..2....0..0....1..1....2..2....0..0....0..0....2..2
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|