A201806 Number of arrays of n integers in -3..3 with sum zero and equal numbers of elements greater than zero and less than zero.

1, 7, 19, 151, 631, 4621, 23857, 164599, 948871, 6359617, 38944357, 258107389, 1636264813, 10819063087, 70033892299, 463844386999, 3042796871863, 20218887555601, 133836585431269, 892623030133681, 5947033694372881

Offset: 1

Author

R. H. Hardin, Dec 05 2011

Keywords

• nonn

Examples

			Some solutions for n=7:
.-3....2....0...-1...-3....3....1....3...-1....3....0...-2....1...-3....0...-3
.-3....3...-2...-1....1....1...-1....2...-3....3....1....3....3...-2....0....3
.-3....0....3...-2...-1....0...-2...-2....1....1...-2...-3....0....1....2....0
..3...-3...-2....2...-1...-1....3...-2....2...-2....2....3....2....0...-3....0
..3....2....3....1....3....1....0....0....0...-2...-2....2...-1....3...-2....0
..3...-3....1....0....1...-1....1....2...-1...-3....3...-3...-3....2....0...-3
..0...-1...-3....1....0...-3...-2...-3....2....0...-2....0...-2...-1....3....3
		

Links

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

Crossrefs

Column 3 of A201811.