A211578 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 three, four, five or six distinct values for every i,j,k<=n.

16, 52, 144, 380, 964, 2456, 6124, 15508, 38608, 97780, 243828, 618200, 1544572, 3919940, 9810928, 24918052, 62460100, 158735704, 398435148, 1013116820, 2546214544, 6477456788, 16299033172, 41482468312, 104500505308, 266074661668

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..59

Formula

Empirical: a(n) = 2*a(n-1) + 12*a(n-2) - 21*a(n-3) - 48*a(n-4) + 64*a(n-5) + 80*a(n-6) - 60*a(n-7) - 48*a(n-8).

Empirical g.f.: 4*x*(4 + 5*x - 38*x^2 - 49*x^3 + 84*x^4 + 116*x^5 - 18*x^6 - 36*x^7) / ((1 - x - x^2)*(1 - 2*x^2)*(1 - x - 4*x^2)*(1 - 6*x^2)). - Colin Barker, Jul 19 2018

Example

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

Crossrefs

Sequence in context: A009931 A009936 A217736 * A211592 A235653 A354886

Adjacent sequences: A211575 A211576 A211577 * A211579 A211580 A211581

Keyword

nonn

Author

R. H. Hardin, Apr 16 2012

Status

approved