A200060 Number of -n..n arrays x(0..5) of 6 elements with zero sum and elements alternately strictly increasing and strictly decreasing.

10, 178, 1098, 4172, 11962, 28554, 59910, 114232, 202314, 337902, 538054, 823496, 1218978, 1753638, 2461350, 3381092, 4557298, 6040218, 7886274, 10158420, 12926498, 16267598, 20266414, 25015604, 30616142, 37177686, 44818926, 53667948

Offset

1,1

Comments

Row 6 of A200057.

Links

R. H. Hardin, Table of n, a(n) for n = 1..200

Formula

Empirical: a(n) = 3*a(n-1) -2*a(n-2) -a(n-3) +2*a(n-5) -a(n-6) -a(n-7) +2*a(n-8) -a(n-10) -2*a(n-11) +3*a(n-12) -a(n-13).

Empirical g.f.: 2*x*(5 + 74*x + 292*x^2 + 622*x^3 + 910*x^4 + 1045*x^5 + 999*x^6 + 782*x^7 + 452*x^8 + 162*x^9 + 24*x^10 + x^11) / ((1 - x)^6*(1 + x)*(1 + x + x^2)*(1 + x + x^2 + x^3 + x^4)). - Colin Barker, May 17 2018

Example

Some solutions for n=6:
..3...-3...-2....4....4...-2...-5....0....1....1....2....1....1...-2...-3...-1
..5...-2...-3....3....5...-6....3....2...-6...-2....5...-6...-2....3....2....6
.-5...-4....3....5...-4....6....2...-3....0....5...-1....1....6...-2....1...-3
.-3....3...-5...-6...-2....0....5....4...-4...-6....2...-2...-6....2....3....0
.-6....1....5...-2...-5....6...-3...-6....6....6...-5....6....1...-3...-6...-2
..6....5....2...-4....2...-4...-2....3....3...-4...-3....0....0....2....3....0

Crossrefs

Cf. A200057.

Sequence in context: A053537 A049380 A302105 * A240561 A057122 A261177

Adjacent sequences: A200057 A200058 A200059 * A200061 A200062 A200063

Keyword

nonn

Author

R. H. Hardin, Nov 13 2011

Status

approved