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A203293 Number of arrays of 6 nondecreasing integers in -n..n with sum zero and equal numbers greater than zero and less than zero. 1
4, 10, 28, 69, 154, 310, 580, 1013, 1680, 2662, 4064, 6005, 8634, 12114, 16644, 22441, 29760, 38878, 50116, 63817, 80374, 100206, 123784, 151609, 184240, 222266, 266340, 317149, 375446, 442022, 517740, 603501, 700284, 809110, 931080, 1067341, 1219126 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 3 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) -4*a(n-3) +2*a(n-4) +2*a(n-5) +2*a(n-6) -4*a(n-7) -a(n-8) +3*a(n-9) -a(n-10).

Empirical g.f.: x*(4 - 2*x + 2*x^2 + 11*x^3 + 7*x^4 + x^5 - 4*x^6 + x^7 + 3*x^8 - x^9) / ((1 - x)^6*(1 + x)^2*(1 + x + x^2)). - Colin Barker, Jun 04 2018

EXAMPLE

Some solutions for n=3:

.-2...-2...-2...-3...-3...-1...-3...-3....0...-2...-1...-3...-2...-3...-3...-3

..0...-2...-2...-2...-1...-1....0...-3....0...-2...-1...-2...-2...-2...-1...-1

..0....0...-1....0....0...-1....0...-1....0....0....0...-2...-2...-1....0...-1

..0....0....1....0....0....1....0....2....0....0....0....2....2....2....0....1

..0....1....2....2....2....1....0....2....0....2....1....2....2....2....1....1

..2....3....2....3....2....1....3....3....0....2....1....3....2....2....3....3

CROSSREFS

Cf. A203291.

Sequence in context: A026534 A034920 A274597 * A111308 A121302 A026150

Adjacent sequences:  A203290 A203291 A203292 * A203294 A203295 A203296

KEYWORD

nonn

AUTHOR

R. H. Hardin, Dec 31 2011

STATUS

approved

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Last modified February 17 12:32 EST 2020. Contains 331996 sequences. (Running on oeis4.)