A188243 Number of arrangements of n+2 nonzero numbers x(i) in -3..3 with the sum of x(i)*x(i+1) equal to zero

36, 52, 548, 1632, 12692, 51196, 355396, 1657632, 10858368, 54754656, 346608044, 1831830172, 11344750308, 61835276360, 377379008580, 2101523967056, 12697531716136, 71809422531596, 430895582983328, 2464705595705660

Offset

1,1

Comments

Column 3 of A188249

Links

R. H. Hardin, Table of n, a(n) for n = 1..124

Example

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

Crossrefs

Sequence in context: A211720 A261285 A261257 * A335104 A242343 A243540

Adjacent sequences: A188240 A188241 A188242 * A188244 A188245 A188246

Keyword

nonn

Author

R. H. Hardin Mar 25 2011

Status

approved