A199839 Number of -n..n arrays x(0..9) of 10 elements with zero sum and no two neighbors summing to zero.

138, 88636, 3685550, 51077518, 389832124, 2044221894, 8281149188, 27785393300, 80752300406, 209581305608, 496408914210, 1090354976530, 2248071267000, 4391976524034, 8191437222152, 14673108432136, 25367684178562

Offset: 1

Author

R. H. Hardin Nov 11 2011

Keywords

• nonn

Comments

Row 8 of A199832

Examples

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

Links

• R. H. Hardin, Table of n, a(n) for n = 1..33

Formula

Empirical: a(n) = (124952/567)*n^9 - (35524/315)*n^8 + (50588/945)*n^7 - (2494/45)*n^6 + (13739/270)*n^5 - (1927/180)*n^4 - (41254/2835)*n^3 + (3319/420)*n^2 - (781/630)*n