A189491 Number of arrangements of n+1 nonzero numbers x(i) in -2..2 with the sum of floor(x(i)/x(i+1)) equal to zero.

2, 12, 42, 136, 550, 1892, 7384, 26816, 103288, 386928, 1485566, 5654000, 21736466, 83448592, 321767288, 1241835856, 4803432344, 18605438864, 72168550344, 280295950240, 1089835505354, 4242072071396, 16526909026016, 64446293812896

Offset

1,1

Comments

Column 2 of A189498

Links

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

Example

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

Crossrefs

Sequence in context: A277935 A290928 A232584 * A301556 A055681 A296682

Adjacent sequences: A189488 A189489 A189490 * A189492 A189493 A189494

Keyword

nonn

Author

R. H. Hardin, Apr 23 2011

Status

approved