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
Keywords
Examples
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
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)
Comments