A211527 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, three, four or five distinct values for every i,j,k<=n.

8, 18, 42, 90, 192, 394, 806, 1618, 3244, 6444, 12798, 25306, 50056, 98830, 195252, 385546, 761880, 1505776, 2978372, 5893812, 11672100, 23128778, 45863610, 91000330, 180675314, 358921836, 713425574, 1418791694, 2822950098, 5619290544

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..63

Formula

Empirical: a(n) = 5*a(n-1) - 4*a(n-2) - 16*a(n-3) + 27*a(n-4) + 8*a(n-5) - 35*a(n-6) + 10*a(n-7) + 10*a(n-8) - 4*a(n-9).

Empirical g.f.: 2*x*(4 - 11*x - 8*x^2 + 40*x^3 - 9*x^4 - 42*x^5 + 23*x^6 + 10*x^7 - 6*x^8) / ((1 - x)*(1 - 2*x)*(1 - x - x^2)*(1 - 2*x^2)*(1 - x - 2*x^2 + x^3)). - Colin Barker, Jul 18 2018

Example

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

Crossrefs

Sequence in context: A096283 A300524 A082194 * A279899 A192311 A300161

Adjacent sequences: A211524 A211525 A211526 * A211528 A211529 A211530

Keyword

nonn

Author

R. H. Hardin, Apr 14 2012

Status

approved