

A351109


Number of simple paths for a Racetrack car (using von Neumann neighborhood) with initial velocity zero, going from one corner to the diagonally opposite corner on an n X n grid.


2




OFFSET

1,3


LINKS



EXAMPLE

For n = 4 the following paths, together with their reflections in the diagonal, exist. The numbers give the positions of the car after successive steps. In total, there are a(4) = 2*4 = 8 possible paths.
...3 ...4 ...4 ...5
.... ...3 ..3. ...4
..2. ..2. ..2. ...3
01.. 01.. 01.. 012.


CROSSREFS



KEYWORD

nonn,more


AUTHOR



STATUS

approved



