A250272 Number of length n+1 0..3 arrays with the sum of the squares of adjacent differences multiplied by some arrangement of +-1 equal to zero.

4, 20, 52, 240, 984, 4412, 20252, 91808, 406748, 1759740, 7455484, 31056840, 127719296, 520368940, 2106440916, 8489650480, 34118389900, 136865613068, 548408972596, 2195889958776, 8788865312160, 35167823753468, 140699850287804

Offset: 1

Author

R. H. Hardin, Nov 16 2014

Keywords

• nonn

Comments

Column 3 of A250277

Examples

			Some solutions for n=6
..2....1....2....0....1....0....1....3....0....1....3....3....3....3....0....0
..3....3....0....2....0....1....3....2....2....1....3....0....0....1....3....2
..1....3....1....3....2....0....2....3....3....3....3....1....3....0....2....0
..0....3....3....2....3....1....0....0....2....3....1....0....1....0....1....1
..0....2....1....3....2....0....1....3....2....0....2....0....3....0....0....0
..2....3....3....2....2....2....0....2....2....1....3....3....1....3....3....0
..2....1....0....2....1....2....3....3....0....3....1....3....3....1....2....0
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..55

Formula

Empirical: a(n) = 22*a(n-1) -221*a(n-2) +1348*a(n-3) -5594*a(n-4) +16756*a(n-5) -37474*a(n-6) +63792*a(n-7) -83421*a(n-8) +83878*a(n-9) -64369*a(n-10) +37052*a(n-11) -15496*a(n-12) +4448*a(n-13) -784*a(n-14) +64*a(n-15) for n>18