A199834 Number of -n..n arrays x(0..4) of 5 elements with zero sum and no two neighbors summing to zero.

4, 114, 646, 2146, 5390, 11384, 21364, 36796, 59376, 91030, 133914, 190414, 263146, 354956, 468920, 608344, 776764, 977946, 1215886, 1494810, 1819174, 2193664, 2623196, 3112916, 3668200, 4294654, 4998114, 5784646, 6660546, 7632340, 8706784

Offset: 1

Author

R. H. Hardin Nov 11 2011

Keywords

• nonn

Comments

Row 3 of A199832

Examples

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

Links

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

Formula

Empirical: a(n) = (115/12)*n^4 - (29/6)*n^3 + (5/12)*n^2 - (7/6)*n.

Empirical: G.f.: -2*x*(2+47*x+58*x^2+8*x^3) / (x-1)^5. - R. J. Mathar, Aug 01 2014