A211504 Number of -3..3 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 two, three or four distinct values for every i<=n and j<=n.

48, 330, 2262, 15474, 105642, 719838, 4895886, 33239874, 225294570, 1524529134, 10300146510, 69486664818, 468097569162, 3149005428126, 21156149373582, 141954447726498, 951332764533354, 6368070500470926, 42578969613094542

Offset

1,1

Links

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

Formula

Empirical: a(n) = 24*a(n-1) - 210*a(n-2) + 756*a(n-3) - 659*a(n-4) - 1164*a(n-5) - 390*a(n-6) - 36*a(n-7).

Empirical g.f.: 6*x*(8 - 137*x + 737*x^2 - 967*x^3 - 1427*x^4 - 460*x^5 - 42*x^6) / ((1 - 6*x)*(1 - 6*x - x^2)*(1 - 6*x - 2*x^2)*(1 - 6*x - 3*x^2)). - Colin Barker, Jul 18 2018

Example

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

Crossrefs

Sequence in context: A211735 A211746 A211755 * A211766 A187164 A110275

Adjacent sequences: A211501 A211502 A211503 * A211505 A211506 A211507

Keyword

nonn

Author

R. H. Hardin, Apr 13 2012

Status

approved