A211724 Number of -3..3 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 or five distinct values for every i,j,k<=n.

36, 66, 104, 178, 280, 476, 768, 1324, 2208, 3880, 6672, 11928, 21008, 38048, 68144, 124512, 225456, 414288, 755312, 1392784, 2549872, 4711856, 8647920, 16000432, 29410032, 54455152, 100180464, 185574000, 341574128, 632894192, 1165280240

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..57

Formula

Empirical: a(n) = a(n-1) + 6*a(n-2) - 6*a(n-3) - 10*a(n-4) + 10*a(n-5) + 4*a(n-6) - 4*a(n-7).

Empirical g.f.: 2*x*(18 + 15*x - 89*x^2 - 53*x^3 + 117*x^4 + 26*x^5 - 42*x^6) / ((1 - x)*(1 - 2*x^2)*(1 - 4*x^2 + 2*x^4)). - Colin Barker, Jul 20 2018

Example

Some solutions for n=5:
..2...-1...-3...-1....2....0....1...-2...-2...-2....0....3....1...-1....1....0
.-3....0...-2....0....0....2...-3...-1...-3....0...-2....0....0...-2....3...-1
..2....1...-1...-1...-2....0....1....0...-2...-2....0...-3...-2...-1....1....0
..0....2...-2....3....0...-1....3....1...-1....3....1....0....0....0...-3....2
..2....1...-1...-1....2....0....1....0....0...-2....0...-3...-2...-1....1....0
.-3....2...-2....0....0....2...-3...-1....1....0...-2....0....0...-2...-3...-1

Crossrefs

Sequence in context: A240520 A126789 A176623 * A250771 A068144 A182428

Adjacent sequences: A211721 A211722 A211723 * A211725 A211726 A211727

Keyword

nonn

Author

R. H. Hardin, Apr 20 2012

Status

approved