A199700 Number of -4..4 arrays x(0..n-1) of n elements with zero sum and no two neighbors equal.

1, 8, 52, 380, 2734, 20116, 149942, 1128388, 8545180, 65055556, 497505902, 3818857188, 29405977172, 227044808964, 1757143904470, 13626887453432, 105870556547144, 823864569255344, 6420445347122416, 50100342760566184

Offset: 1

Author

R. H. Hardin Nov 09 2011

Keywords

• nonn

Comments

Column 4 of A199704

Examples

			Some solutions for n=5
..2...-1....3....1...-1....1....3....0...-4...-4....3....4....3....0...-1...-1
.-2....3...-4....0....1....2....1...-4....1....3...-4....0...-1...-3....0....4
..0....0....1....1...-4...-3...-4....4....0...-2...-2...-4....0....2....4...-2
..3....2...-1....2....3...-2....1...-4....2...-1....0...-1...-2....3...-1....1
.-3...-4....1...-4....1....2...-1....4....1....4....3....1....0...-2...-2...-2
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..200