|
|
A221083
|
|
Number of n X 4 arrays of occupancy after each element moves to some horizontal or antidiagonal neighbor.
|
|
1
|
|
|
4, 169, 6889, 279841, 11363641, 461433361, 18736955689, 760832274049, 30894332043289, 1254494297783281, 50939956897994761, 2068466324059544161, 83992079976098560249, 3410579817835188926929, 138489899251625571693289
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
|
|
LINKS
|
|
|
FORMULA
|
Empirical: a(n) = 45*a(n-1) - 180*a(n-2) + 64*a(n-3).
Empirical g.f.: x*(4 - 11*x + 4*x^2) / ((1 - 4*x)*(1 - 41*x + 16*x^2)). - Colin Barker, Aug 03 2018
|
|
EXAMPLE
|
Some solutions for n=3:
..0..1..2..0....0..2..1..0....0..2..3..1....0..3..1..0....0..1..2..1
..1..3..2..1....0..1..2..0....0..2..0..0....2..2..1..1....0..3..2..0
..0..0..1..1....1..3..2..0....0..0..3..1....1..0..1..0....1..1..1..0
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|