A200061 Number of -n..n arrays x(0..6) of 7 elements with zero sum and elements alternately strictly increasing and strictly decreasing.

14, 472, 4224, 20978, 74338, 211242, 514168, 1115572, 2215290, 4099888, 7165376, 11941380, 19119208, 29580842, 44432366, 65037696, 93057524, 130487666, 179703518, 243503094, 325156994, 428455996, 557766736, 718083722, 915090720

Offset: 1

Author

R. H. Hardin Nov 13 2011

Keywords

• nonn

Comments

Row 7 of A200057

Examples

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

Links

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

Formula

Empirical: a(n) = 2*a(n-1) -a(n-3) -a(n-5) +a(n-6) -2*a(n-7) +2*a(n-8) +a(n-9) -a(n-13) -2*a(n-14) +2*a(n-15) -a(n-16) +a(n-17) +a(n-19) -2*a(n-21) +a(n-22)