A188349 Number of arrangements of n+1 numbers x(i) in -n..n with the sum of x(i)*x(i+1) equal to zero.

5, 45, 257, 4201, 45801, 1171345, 25217201, 870473329, 30807035021, 1370460938381

Offset: 1

Author

R. H. Hardin Mar 28 2011

Keywords

• nonn

Comments

Diagonal of A188358

Examples

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