OFFSET
1,2
LINKS
Wikipedia, Racetrack
EXAMPLE
For n = 3 the following paths exist (up to reflection in the diagonal). The numbers give the positions of the car after successive steps.
..2 ..3 ..3 ..3 ..4 ..4 .34 .56 456 548 678 678
.1. ..2 .2. .12 ..3 .23 .2. .43 32. 673 543 512
0.. 01. 01. 0.. 012 01. 01. 012 01. 012 012 043
Of these, only the first path is symmetric with respect to the diagonal, so the other 11 give rise to 2 paths each. In total, there are a(3) = 1 + 2*11 = 23 possible paths.
CROSSREFS
KEYWORD
nonn,more
AUTHOR
Pontus von Brömssen, Feb 01 2022
STATUS
approved