

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

Table of n, a(n) for n=1..8.
Wikipedia, Racetrack


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

Main diagonal of A351108.
Cf. A007764, A351042, A351107.
Sequence in context: A140363 A280921 A208962 * A012597 A012534 A092354
Adjacent sequences: A351106 A351107 A351108 * A351110 A351111 A351112


KEYWORD

nonn,more


AUTHOR

Pontus von Brömssen, Feb 01 2022


STATUS

approved



