A211573 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 or six distinct values for every i,j,k<=n.

16, 44, 108, 260, 604, 1436, 3324, 7964, 18556, 44924, 105468, 257660, 608764, 1497596, 3555324, 8790524, 20940796, 51959804, 124076028, 308619260, 738172924, 1839144956, 4403888124, 10984562684, 26322698236, 65706098684, 157533601788

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..72

Formula

Empirical: a(n) = 3*a(n-1) + 6*a(n-2) - 24*a(n-3) + 4*a(n-4) + 36*a(n-5) - 24*a(n-6).

Empirical g.f.: 4*x*(4 - x - 30*x^2 + 14*x^3 + 42*x^4 - 24*x^5) / ((1 - x)*(1 - 2*x)*(1 - 2*x^2)*(1 - 6*x^2)). - Colin Barker, Jul 19 2018

Example

Some solutions for n=5:
..0....0....1...-1....0....1...-1....2....0....1...-1....1....2...-1...-2....0
..1....1....2....2....1....2...-2....1....1....2...-2...-2....1....2...-1...-1
..2....2...-1....1....2....0....1....2...-2....0....1....1...-2...-1....2....2
.-1....0...-2....2....1....2....0....1...-1....1....2....0....1...-2...-1....1
..2....2....1....1...-2....0....1...-2...-2....0....1...-1....2....1...-2...-2
..1....0....0....0...-1....1....2...-1....1....1...-2....0....1....0....1....1

Crossrefs

Sequence in context: A173560 A293858 A258547 * A211582 A204032 A192143

Adjacent sequences: A211570 A211571 A211572 * A211574 A211575 A211576

Keyword

nonn

Author

R. H. Hardin, Apr 16 2012

Status

approved