A211569 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, four or five distinct values for every i,j,k<=n.

24, 52, 94, 174, 304, 552, 980, 1802, 3286, 6158, 11512, 21948, 41836, 80838, 156278, 304946, 595408, 1169984, 2300260, 4542522, 8974198, 17784654, 35255336, 70043180, 139186780, 277026950, 551453398, 1099000626, 2190431680, 4369469520

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..64

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 - 22*x - 69*x^2 + 125*x^3 + 111*x^4 - 196*x^5 - 37*x^6 + 58*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....2....2....0...-1....1....2...-1....1...-1....2...-1....2...-2...-2...-2
.-2....1...-2...-1...-2...-1....1....0...-2....1...-2...-1....0....2...-2....1
.-2....0....2....0...-1....1....0...-1....1...-1....2...-1....2....2...-2...-2
.-2...-1....2...-1....0....1....1....0...-2...-1....0....1....0....2...-2...-2
.-2....0....2....0....1....1....2...-1...-2....1....2....1....2...-2...-2....1
.-2...-1....2....1....0....1....1...-2...-2....1....0....1...-2...-2....2...-2

Crossrefs

Sequence in context: A025137 A070197 A190524 * A084586 A259023 A301575

Adjacent sequences: A211566 A211567 A211568 * A211570 A211571 A211572

Keyword

nonn

Author

R. H. Hardin, Apr 16 2012

Status

approved