A211531 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 one, two, three, four, five or six distinct values for every i,j,k<=n.

9, 27, 77, 199, 503, 1239, 3021, 7303, 17583, 42217, 101245, 242683, 581751, 1395031, 3347035, 8035199, 19302063, 46395265, 111581119, 268493349, 646366887, 1556696779, 3750472401, 9038662155, 21789121821, 52538282553, 126706173657

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..55

Formula

Empirical: a(n) = 5*a(n-1) - 3*a(n-2) - 17*a(n-3) + 17*a(n-4) + 22*a(n-5) - 18*a(n-6) - 14*a(n-7) + 3*a(n-8) + 2*a(n-9).

Empirical g.f.: x*(9 - 18*x - 31*x^2 + 48*x^3 + 45*x^4 - 27*x^5 - 23*x^6 + x^7 + 2*x^8) / ((1 + x)*(1 - 2*x)*(1 - x - x^2)*(1 - 2*x - x^2)*(1 - x - 2*x^2 + x^3)). - Colin Barker, Jul 18 2018

Example

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

Crossrefs

Sequence in context: A198956 A110205 A319085 * A264959 A370870 A053702

Adjacent sequences: A211528 A211529 A211530 * A211532 A211533 A211534

Keyword

nonn

Author

R. H. Hardin, Apr 14 2012

Status

approved