A211568 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 two, three or four distinct values for every i,j,k<=n.

24, 44, 78, 142, 256, 472, 868, 1626, 3046, 5790, 11016, 21196, 40828, 79318, 154246, 301890, 591328, 1163856, 2292084, 4530250, 8957830, 17760094, 35222584, 69994044, 139121260, 276928662, 551322342, 1098804034, 2190169552, 4369076320

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..65

Formula

Empirical: a(n) = 4*a(n-1) + a(n-2) - 21*a(n-3) + 16*a(n-4) + 29*a(n-5) - 34*a(n-6) - 6*a(n-7) + 12*a(n-8).

Empirical g.f.: 2*x*(12 - 26*x - 61*x^2 + 145*x^3 + 75*x^4 - 228*x^5 - x^6 + 82*x^7) / ((1 - x)*(1 - 2*x)*(1 - x - x^2)*(1 - 2*x^2)*(1 - 3*x^2)). - Colin Barker, Jul 19 2018

Example

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

Crossrefs

Sequence in context: A072096 A055480 A322843 * A324459 A324457 A357876

Adjacent sequences: A211565 A211566 A211567 * A211569 A211570 A211571

Keyword

nonn

Author

R. H. Hardin, Apr 16 2012

Status

approved