A200556 Number of -n..n arrays x(0..5) of 6 elements with zero sum and nonzero second differences

72, 1240, 7254, 26850, 75792, 178834, 372150, 705270, 1242888, 2067650, 3281874, 5009232, 7397868, 10621792, 14882672, 20413220, 27478160, 36376230, 47443518, 61054528, 77624122, 97610834, 121518006, 149895400, 183343046, 222512226

Offset

1,1

Comments

Row 4 of A200553

Links

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

Formula

Empirical: a(n) = a(n-1) +a(n-2) +a(n-3) -2*a(n-4) -a(n-6) -a(n-7) -a(n-8) +3*a(n-9) +3*a(n-10) -a(n-11) -a(n-12) -a(n-13) -2*a(n-15) +a(n-16) +a(n-17) +a(n-18) -a(n-19)

Example

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

Crossrefs

Sequence in context: A168194 A249713 A269074 * A239423 A128800 A367781

Adjacent sequences: A200553 A200554 A200555 * A200557 A200558 A200559

Keyword

nonn

Author

R. H. Hardin Nov 19 2011

Status

approved