|
|
A264185
|
|
Number of (n+1) X (3+1) arrays of permutations of 0..n*4+3 with each element having index change +-(.,.) 0,0 1,-1 or 2,2.
|
|
1
|
|
|
8, 81, 720, 7056, 70560, 705600, 7056000, 70560000, 705600000, 7056000000, 70560000000, 705600000000, 7056000000000, 70560000000000, 705600000000000, 7056000000000000, 70560000000000000, 705600000000000000
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
FORMULA
|
Empirical: a(n) = 10*a(n-1) for n>4.
G.f.: x*(8 + x - 90*x^2 - 144*x^3) / (1 - 10*x).
a(n) = 441*2^n * 5^(n-4) for n>3.
(End)
|
|
EXAMPLE
|
Some solutions for n=4:
..0.11..2..6...10.11..2..3....0.11..2..6....0..1..2..6...10..4..2..3
..1..5..3..7....4..8..6..7....1..5..3..7....4.15..3.10....1.15..6..7
.18..9.10.14...18.12..0..1....8.19.13.14....5.19..7.11...18..9..0.11
.12.16..4.15....9.16.14..5...12.10..4.18...12.13.17.18...12.13.17..5
.13.17..8.19...13.17.15.19...16.17.15..9...16.14..8..9...16.14..8.19
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|