A211532 Number of -1..1 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 two, four, five, six or seven distinct values for every i,j,k<=n.

8, 22, 46, 100, 204, 422, 856, 1744, 3526, 7136, 14388, 29006, 58352, 117336, 235638, 473000, 948684, 1902030, 3811400, 7635312, 15290470, 30614320, 61281860, 122652366, 245446592, 491127784, 982632022, 1965883288, 3932762268

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..58

Formula

Empirical: a(n) = 3*a(n-1) + 2*a(n-2) - 11*a(n-3) + a(n-4) + 12*a(n-5) - 2*a(n-6) - 4*a(n-7).

Empirical g.f.: 2*x*(4 - x - 18*x^2 + 3*x^3 + 23*x^4 - x^5 - 6*x^6) / ((1 - x)*(1 + x)*(1 - 2*x)*(1 - x - x^2)*(1 - 2*x^2)). - Colin Barker, Jul 19 2018

Example

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

Crossrefs

Sequence in context: A112684 A189584 A239360 * A269429 A305181 A048489

Adjacent sequences: A211529 A211530 A211531 * A211533 A211534 A211535

Keyword

nonn

Author

R. H. Hardin, Apr 14 2012

Status

approved