A188350 Number of arrangements of n+1 numbers x(i) in -1..1 with the sum of x(i)*x(i+1) equal to zero

5, 15, 29, 91, 197, 627, 1477, 4671, 11693, 36487, 95405, 293695, 792525, 2412175, 6660989, 20097243, 56450693, 169229571, 481426405, 1436666475, 4126292293, 12275100443, 35511918037, 105423983379, 306684489749, 909271908483

Offset

1,1

Comments

Column 1 of A188358

Links

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

Example

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

Crossrefs

Sequence in context: A298025 A162525 A212871 * A268222 A285630 A078905

Adjacent sequences: A188347 A188348 A188349 * A188351 A188352 A188353

Keyword

nonn

Author

R. H. Hardin Mar 28 2011

Status

approved