|
|
A264423
|
|
Number of (2+1) X (n+1) arrays of permutations of 0..n*3+2 with each element having directed index change 0,1 2,2 1,0 -1,2 -2,-1 or -1,-1.
|
|
1
|
|
|
1, 3, 12, 37, 119, 385, 1252, 4061, 13166, 42687, 138419, 448847, 1455443, 4719435, 15303308, 49622768, 160907641, 521761825, 1691873630, 5486097814, 17789312907, 57683924784, 187046863084, 606521298870, 1966716147754, 6377306803896
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,2
|
|
LINKS
|
|
|
FORMULA
|
Empirical: a(n) = 3*a(n-1) + a(n-3) + 5*a(n-4) + a(n-7).
Empirical g.f.: x*(1 + 3*x^2 + x^5) / ((1 + x^2 + x^3)*(1 - 3*x - x^2 + x^3 - x^4)). - Colin Barker, Jan 07 2019
|
|
EXAMPLE
|
Some solutions for n=4:
..6..7..1..2..3....6..0..1..9..3....6.12.13.14..7...11.12.13..2..3
..0.12.13.14..4...11.12..2.14..4....0..1..2..3..4....0..1..6.14..4
..5.10.11..8..9....5.10..7..8.13....5.10.11..8..9....5.10..7..8..9
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|