|
|
A207689
|
|
Number of n X 4 0..1 arrays avoiding 0 0 0 and 0 1 0 horizontally and 0 0 1 and 1 1 1 vertically.
|
|
1
|
|
|
9, 81, 100, 256, 576, 1156, 2500, 5476, 11664, 24964, 53824, 115600, 248004, 532900, 1144900, 2458624, 5280804, 11343424, 24364096, 52330756, 112402404, 241429444, 518563984, 1113823876, 2392383744, 5138595856, 11037183364, 23706760900
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
|
|
LINKS
|
|
|
FORMULA
|
Empirical: a(n) = a(n-1) + a(n-2) + 3*a(n-3) + a(n-4) - a(n-5) - a(n-6) for n>8.
Empirical g.f.: x*(9 + 72*x + 10*x^2 + 48*x^3 - 32*x^4 - 48*x^5 - 10*x^6 + 17*x^7) / ((1 + x^2 - x^3)*(1 - x - 2*x^2 - x^3)). - Colin Barker, Jun 25 2018
|
|
EXAMPLE
|
Some solutions for n=4:
..1..0..0..1....1..1..1..1....1..1..1..0....1..1..0..1....0..0..1..1
..1..1..1..1....0..0..1..1....1..0..0..1....0..0..1..1....1..1..1..0
..0..1..1..0....1..1..0..0....0..1..1..0....1..1..0..0....1..1..0..1
..1..0..0..1....1..0..0..1....0..1..1..1....0..1..1..0....0..0..1..1
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|