A202080 Number of arrays of 9 integers in -n..n with sum zero and the sum of every adjacent pair being odd

6, 726, 8412, 80812, 340660, 1516410, 4213042, 12861252, 28421280, 69306670, 132493530, 278307730, 481381744, 909136644, 1461430338, 2548699638, 3874036128, 6350628468, 9236088510, 14409332790, 20220953874, 30295374604

Offset

1,1

Comments

Row 7 of A202076

Links

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

Formula

Empirical: a(n) = a(n-1) +8*a(n-2) -8*a(n-3) -28*a(n-4) +28*a(n-5) +56*a(n-6) -56*a(n-7) -70*a(n-8) +70*a(n-9) +56*a(n-10) -56*a(n-11) -28*a(n-12) +28*a(n-13) +8*a(n-14) -8*a(n-15) -a(n-16) +a(n-17)

Example

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

Crossrefs

Sequence in context: A080369 A036981 A343434 * A271528 A316748 A354251

Adjacent sequences: A202077 A202078 A202079 * A202081 A202082 A202083

Keyword

nonn

Author

R. H. Hardin Dec 10 2011

Status

approved