A201871 Number of zero-sum -6..6 arrays of n elements with first and second differences also in -6..6

1, 7, 47, 285, 1905, 13635, 99143, 734607, 5477087, 40989699, 307950303, 2320964021, 17543356961, 132967038437, 1010302510909, 7693410001853, 58699664900479, 448643950237839, 3434254414420963, 26324281838259421

Offset

1,2

Comments

Column 6 of A201873

Links

R. H. Hardin, Table of n, a(n) for n = 1..210

Example

Some solutions for n=7
.-2....2....4....2...-5....1...-1...-1....2...-3....4...-3...-1...-2...-5....3
.-2....2....2....0...-2....3....2....2....4...-3....6...-1...-4....4...-1....5
..4...-2....2....0....0....1....0....2....1....2....4....3...-3....6....2....2
..4...-3....1...-2....4....2...-2....0...-2....2....0....2...-2....2....3...-2
..1....0....0....2....3....0....2....1...-4....0...-3....2....2...-3....0...-3
..0....2...-5....1....0...-1....2....1...-1....1...-6....0....4...-4...-1...-2
.-5...-1...-4...-3....0...-6...-3...-5....0....1...-5...-3....4...-3....2...-3

Crossrefs

Sequence in context: A064385 A269520 A009260 * A198845 A323131 A229010

Adjacent sequences: A201868 A201869 A201870 * A201872 A201873 A201874

Keyword

nonn

Author

R. H. Hardin Dec 06 2011

Status

approved