A199709 Number of -n..n arrays x(0..6) of 7 elements with zero sum and no two neighbors equal

56, 2642, 27854, 149942, 559028, 1643204, 4099204, 9059092, 18251656, 34171380, 60292468, 101279218, 163252890, 254042820, 383508158, 563826638, 809873706, 1139548482, 1574209250, 2139036592, 2863528108, 3781894246, 4933615190

Offset

1,1

Comments

Row 7 of A199704

Links

R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n)=2*a(n-1)-a(n-3)-a(n-5)+a(n-6)-2*a(n-7)+2*a(n-8)+a(n-9)-a(n-13)-2*a(n-14)+2*a(n-15)-a(n-16)+a(n-17)+a(n-19)-2*a(n-21)+a(n-22)

Example

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

Crossrefs

Sequence in context: A124101 A198948 A003696 * A205227 A328352 A224176

Adjacent sequences: A199706 A199707 A199708 * A199710 A199711 A199712

Keyword

nonn

Author

R. H. Hardin Nov 09 2011

Status

approved