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

1,1

Comments

Row 6 of A203291

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)

Example

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

Crossrefs

Sequence in context: A304520 A335759 A224663 * A355155 A058822 A054369

Adjacent sequences: A203293 A203294 A203295 * A203297 A203298 A203299

Keyword

nonn

Author

R. H. Hardin Dec 31 2011

Status

approved