A211463 Number of -2..2 arrays x(i) of n+1 elements i=1..n+1 with x(i)+x(j), x(i+1)+x(j+1), -(x(i)+x(j+1)), and -(x(i+1)+x(j)) having three or four distinct values for every i<=n and j<=n.

20, 80, 304, 1144, 4232, 15536, 56616, 205400, 742608, 2678752, 9648024, 34716712, 124861664, 449008336, 1614830152, 5809328408, 20907961552, 75287770240, 271263934328, 977981837448, 3528166785472, 12736459731632, 46007299834152

Offset

1,1

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Formula

Empirical: a(n) = 5*a(n-1) + 9*a(n-2) - 57*a(n-3) - 36*a(n-4) + 196*a(n-5) + 96*a(n-6) - 124*a(n-7) + 24*a(n-8).

Empirical g.f.: 4*x*(5 - 5*x - 69*x^2 + 11*x^3 + 264*x^4 + 92*x^5 - 150*x^6 + 30*x^7) / ((1 - 2*x - 6*x^2)*(1 - x - 6*x^2 + 2*x^3)*(1 - 2*x - 5*x^2 + 2*x^3)). - Colin Barker, Jul 17 2018

Example

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

Crossrefs

Sequence in context: A002609 A195322 A200424 * A244449 A041776 A103532

Adjacent sequences: A211460 A211461 A211462 * A211464 A211465 A211466

Keyword

nonn

Author

R. H. Hardin, Apr 12 2012

Status

approved