A203296 Number of arrays of 12 nondecreasing integers in -n..n with sum zero and equal numbers greater than zero and less than zero.

7, 28, 176, 944, 4206, 15798, 51768, 151393, 403131, 991692, 2280620, 4948566, 10208256, 20143302, 38215998, 70007951, 124283183, 214475760, 360744276, 592751998, 953388836, 1503671490, 2329136950, 3548069499, 5322005825

Offset: 1

Author

R. H. Hardin Dec 31 2011

Keywords

• nonn

Comments

Row 6 of A203291

Examples

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

Links

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

Formula

Empirical: a(n) = 3*a(n-1) -a(n-2) -3*a(n-3) +a(n-4) -a(n-5) +3*a(n-6) -a(n-7) +5*a(n-8) -a(n-9) -6*a(n-10) -2*a(n-11) -a(n-12) +a(n-13) +a(n-14) +13*a(n-15) -4*a(n-16) -2*a(n-17) -4*a(n-18) -4*a(n-19) -2*a(n-20) -4*a(n-21) +13*a(n-22) +a(n-23) +a(n-24) -a(n-25) -2*a(n-26) -6*a(n-27) -a(n-28) +5*a(n-29) -a(n-30) +3*a(n-31) -a(n-32) +a(n-33) -3*a(n-34) -a(n-35) +3*a(n-36) -a(n-37)