A188244 Number of arrangements of n+2 nonzero numbers x(i) in -4..4 with the sum of x(i)*x(i+1) equal to zero.

64, 144, 1504, 7092, 58824, 368588, 2880240, 20265640, 156028036, 1154193268, 8877588920, 67251222980, 518783061524, 3979996140580, 30813430250120, 238176520092556, 1850203922639624, 14371954026347848, 111969329295785092

Offset: 1

Author

R. H. Hardin Mar 25 2011

Keywords

• nonn

Comments

Column 4 of A188249

Examples

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

Links

• R. H. Hardin, Table of n, a(n) for n = 1..59