A211574 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 six distinct values for every i,j,k<=n.

24, 76, 192, 456, 1046, 2408, 5458, 12624, 28762, 67278, 154580, 365720, 847122, 2024242, 4721206, 11375392, 26680354, 64720018, 152478042, 371900846, 879299028, 2154128424, 5107422788, 12556963016, 29839050584, 73573746366

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..41

Formula

Empirical: a(n) = 6*a(n-1) - 3*a(n-2) - 46*a(n-3) + 88*a(n-4) + 49*a(n-5) - 231*a(n-6) + 82*a(n-7) + 168*a(n-8) - 100*a(n-9) - 36*a(n-10) + 24*a(n-11).

Empirical g.f.: 2*x*(12 - 34*x - 96*x^2 + 318*x^3 + 135*x^4 - 766*x^5 + 24*x^6 + 634*x^7 - 72*x^8 - 144*x^9 + 24*x^10) / ((1 - x)*(1 - 2*x)*(1 - x - x^2)*(1 - 2*x^2)*(1 - 6*x^2)*(1 - 2*x - x^2 + x^3)). - Colin Barker, Jul 19 2018

Example

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

Crossrefs

Sequence in context: A291630 A195027 A325958 * A211588 A211596 A214397

Adjacent sequences: A211571 A211572 A211573 * A211575 A211576 A211577

Keyword

nonn

Author

R. H. Hardin, Apr 16 2012

Status

approved