A211690 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, two or three distinct values for every i<=n and j<=n

81, 233, 579, 1373, 3147, 7161, 16061, 36193, 81085, 183171, 413329, 940933, 2145151, 4930245, 11361373, 26362361, 61352875, 143585559, 336993507, 794383691, 1877216725, 4450883361, 10574607261, 25186420645, 60085979449

Offset

1,1

Links

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

Formula

Empirical: a(n) = 6*a(n-1) +11*a(n-2) -127*a(n-3) +27*a(n-4) +1183*a(n-5) -1132*a(n-6) -6381*a(n-7) +8929*a(n-8) +22055*a(n-9) -38648*a(n-10) -51000*a(n-11) +107487*a(n-12) +79800*a(n-13) -203031*a(n-14) -83121*a(n-15) +265573*a(n-16) +54369*a(n-17) -240368*a(n-18) -18623*a(n-19) +148011*a(n-20) +317*a(n-21) -59912*a(n-22) +2112*a(n-23) +15014*a(n-24) -650*a(n-25) -2080*a(n-26) +60*a(n-27) +120*a(n-28)

Example

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

Crossrefs

Sequence in context: A062532 A075730 A184068 * A205055 A335843 A255625

Adjacent sequences: A211687 A211688 A211689 * A211691 A211692 A211693

Keyword

nonn

Author

R. H. Hardin Apr 18 2012

Status

approved