A188245 Number of arrangements of n+2 nonzero numbers x(i) in -5..5 with the sum of x(i)*x(i+1) equal to zero

100, 208, 3292, 16484, 193232, 1399640, 14715004, 123729664, 1247614580, 11199296500, 110995324320, 1029900778912, 10129893228408, 95800929304216, 939159329686860, 8989025842005012, 88016972322771816, 849227228527469216

Offset

1,1

Comments

Column 5 of A188249

Links

R. H. Hardin, Table of n, a(n) for n = 1..42

Example

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

Crossrefs

Sequence in context: A308306 A235272 A249702 * A122467 A185792 A027604

Adjacent sequences: A188242 A188243 A188244 * A188246 A188247 A188248

Keyword

nonn

Author

R. H. Hardin Mar 25 2011

Status

approved