|
| |
|
|
A211576
|
|
Number of -2..2 arrays x(i) of n+1 elements i=1..n+1 with set{t,u,v in 0,1}((x[i+t]+x[j+u]+x[k+v])*(-1)^(t+u+v)) having four, five or six distinct values for every i,j,k<=n.
|
|
1
|
|
|
|
16, 48, 124, 294, 680, 1578, 3600, 8458, 19460, 46510, 108280, 262542, 617264, 1512270, 3580596, 8834026, 21015224, 52087762, 124294096, 308994090, 738810308, 1840241022, 4405749912, 10987766974, 26328139088, 65715472894, 157549520692
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
|
OFFSET
|
1,1
|
|
|
LINKS
|
|
|
|
FORMULA
|
Empirical: a(n) = 4*a(n-1) + 7*a(n-2) - 45*a(n-3) + 10*a(n-4) + 155*a(n-5) - 130*a(n-6) - 180*a(n-7) + 216*a(n-8) + 36*a(n-9) - 72*a(n-10).
Empirical g.f.: 2*x*(8 - 8*x - 90*x^2 + 91*x^3 + 318*x^4 - 290*x^5 - 421*x^6 + 286*x^7 + 186*x^8 - 60*x^9) / ((1 - x)*(1 - 2*x)*(1 - x - x^2)*(1 - 2*x^2)*(1 - 3*x^2)*(1 - 6*x^2)). - Colin Barker, Jul 19 2018
|
|
|
EXAMPLE
|
Some solutions for n=5:
.-2....1...-2...-1...-1...-2....1...-1....0....0...-2....0...-2....0....0....2
..0....0....1....2...-2...-1....0....0....2...-1....0....2...-1....1....2....1
.-2....1...-2....0....1....2...-1...-1....1....0...-2....1....2...-2....1....0
..0....2....1....2...-2....0....2....2....2....1...-1....2...-1...-1....2....2
.-2....1...-2...-1...-1....2...-1...-1....0....0...-2....1....0...-2....0....0
..0....2....0....2....2...-1....0....2....1....1....0....2....1...-1....2....1
|
|
|
CROSSREFS
|
|
|
|
KEYWORD
|
nonn
|
|
|
AUTHOR
|
|
|
|
STATUS
|
approved
|
| |
|
|
