|
|
A218806
|
|
Hilltop maps: number of n X 4 binary arrays indicating the locations of corresponding elements not exceeded by any horizontal or antidiagonal neighbor in a random 0..3 n X 4 array.
|
|
1
|
|
|
15, 249, 3969, 63499, 1015887, 16252713, 260019585, 4159932363, 66552822351, 1064747639097, 17034402072321, 272525472991467, 4360008241786383, 69753743236473129, 1115957683030959873, 17853687738218017899
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
|
|
LINKS
|
|
|
FORMULA
|
Empirical: a(n) = 15*a(n-1) + 15*a(n-2) + 15*a(n-3) + 9*a(n-4) + 9*a(n-5) + 9*a(n-6) + 9*a(n-7).
Empirical g.f.: x*(15 + 24*x + 9*x^2 + 4*x^3 - 3*x^4 + 12*x^5 + 3*x^6) / (1 - 15*x - 15*x^2 - 15*x^3 - 9*x^4 - 9*x^5 - 9*x^6 - 9*x^7). - Colin Barker, Jul 24 2018
|
|
EXAMPLE
|
Some solutions for n=3:
..0..0..1..0....1..0..1..0....1..0..1..0....1..0..0..0....1..0..1..0
..1..1..1..0....1..0..1..0....0..0..0..1....1..0..1..1....0..1..1..0
..1..0..0..0....1..0..0..0....0..1..1..1....0..1..1..0....1..1..1..0
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|