A203288 Number of arrays of 2n nondecreasing integers in -5..5 with sum zero and equal numbers greater than zero and less than zero

6, 35, 154, 544, 1614, 4206, 9880, 21363, 43136, 82267, 149456, 260438, 437670, 712512, 1127794, 1741011, 2628022, 3887553, 5646312, 8065104, 11345704, 15738920, 21553576, 29166921, 39036102, 51711323, 67850258, 88234392

Offset

1,1

Comments

Column 5 of A203291

Links

R. H. Hardin, Table of n, a(n) for n = 1..145

Formula

Empirical: a(n) = 4*a(n-1) -4*a(n-2) -2*a(n-3) +3*a(n-4) +7*a(n-6) -10*a(n-7) +a(n-8) -a(n-10) +10*a(n-11) -7*a(n-12) -3*a(n-14) +2*a(n-15) +4*a(n-16) -4*a(n-17) +a(n-18)

Example

Some solutions for n=3
.-5...-3...-3...-3...-5...-5...-3...-5...-5...-3...-4...-5...-4...-5...-5...-3
.-4...-1...-2...-3...-4...-5...-2....0...-2...-3...-2...-4...-4...-5...-3...-3
.-2...-1....0...-3...-2...-4...-2....0...-1...-1...-1...-1...-3...-2...-2...-2
..1....1....0....2....3....4....1....0....2....1....2....1....3....4....2....2
..5....2....1....2....3....5....1....0....3....2....2....4....4....4....3....3
..5....2....4....5....5....5....5....5....3....4....3....5....4....4....5....3

Crossrefs

Sequence in context: A161784 A027985 A078799 * A026957 A026987 A030532

Adjacent sequences: A203285 A203286 A203287 * A203289 A203290 A203291

Keyword

nonn

Author

R. H. Hardin Dec 31 2011

Status

approved