A211688 Number of -4..4 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 one or three distinct values for every i<=n and j<=n

69, 173, 375, 765, 1545, 3029, 5973, 11621, 22759, 44341, 86833, 169841, 333421, 654917, 1289687, 2542733, 5021945, 9931349, 19663237, 38977973, 77326087, 153558325, 305104801, 606719185, 1206917981, 2402499477, 4783531511

Offset

1,1

Links

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

Formula

Empirical: a(n) = 3*a(n-1) +10*a(n-2) -35*a(n-3) -35*a(n-4) +160*a(n-5) +45*a(n-6) -365*a(n-7) +6*a(n-8) +437*a(n-9) -55*a(n-10) -260*a(n-11) +30*a(n-12) +60*a(n-13)

Example

Some solutions for n=5
.-2...-4....4....1....2....2....0....0....2...-4....1....0....3....0....0....0
..2....0....2....2....0....0....3....0....0...-3....0....4....2....2...-1...-3
..0....4....4....1....0....0....0....4....2...-2....1...-4....1...-2....1....0
.-2....0....2....2....2....0....0....0...-2...-1....2....4....2....0....0....0
..2....0....0....3....0...-4....0....0....0....0....3....0....1...-2....1...-3
.-2....4....2....4...-1....0....0...-4....2...-1....4....4....0....0...-1....0

Crossrefs

Sequence in context: A044782 A020296 A259637 * A153672 A283053 A249899

Adjacent sequences: A211685 A211686 A211687 * A211689 A211690 A211691

Keyword

nonn

Author

R. H. Hardin Apr 18 2012

Status

approved