A203294 Number of arrays of 8 nondecreasing integers in -n..n with sum zero and equal numbers greater than zero and less than zero.

5, 15, 57, 188, 544, 1380, 3172, 6687, 13163, 24435, 43195, 73194, 119616, 189346, 291486, 437723, 642977, 925889, 1309647, 1822576, 2499166, 3380806, 4517000, 5966265, 7797585, 10091447, 12941561, 16456084, 20759580, 25994452, 32323204

Offset

1,1

Comments

Row 4 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) +7*a(n-6) -3*a(n-7) -2*a(n-8) -2*a(n-9) -3*a(n-10) +7*a(n-11) -3*a(n-14) -a(n-15) +3*a(n-16) -a(n-17).

Example

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

Crossrefs

Cf. A203291.

Sequence in context: A309117 A307349 A343841 * A149589 A110614 A149590

Adjacent sequences: A203291 A203292 A203293 * A203295 A203296 A203297

Keyword

nonn

Author

R. H. Hardin, Dec 31 2011

Status

approved