|
|
A264670
|
|
Number of (n+1) X (2+1) arrays of permutations of 0..n*3+2 with each element having directed index change -1,-1 1,0 -1,-2 -2,-2 or 0,1.
|
|
1
|
|
|
1, 2, 9, 19, 44, 108, 264, 649, 1573, 3837, 9353, 22801, 55571, 135432, 330113, 804604, 1961113, 4779902, 11650318, 28396001, 69211142, 168692149, 411162676, 1002149647, 2442594935, 5953472042, 14510727488, 35367800720, 86203902041
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
FORMULA
|
Empirical: a(n) = 2*a(n-1) + a(n-3) + 3*a(n-4) + 2*a(n-5) - a(n-6) + 4*a(n-7) - a(n-8) - a(n-10).
Empirical g.f.: x*(1 + 5*x^2 + x^4 + 3*x^5 - x^6 - x^8) / (1 - 2*x - x^3 - 3*x^4 - 2*x^5 + x^6 - 4*x^7 + x^8 + x^10). - Colin Barker, Jan 08 2019
|
|
EXAMPLE
|
Some solutions for n=4:
..5..0..1....4..0..1....5..0..1....4..0..1....4..0..1....5..0..1....8..0..1
.11..3..2...11..8..2....8..3..2....8..3..2....7..8..2...11..8..2...11..3..2
.10..4..7....3..6..5...11..4..7...14.11..5....3..6..5....3..4..7...14..4..5
..6.14..8...14..7.10....6.14.10....6..7.10...13.14.10....6.14.10....6..7.10
..9.12.13....9.12.13....9.12.13....9.12.13....9.12.11....9.12.13....9.12.13
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|