|Journal of Integer Sequences, Vol. 8 (2005), Article 05.4.3|
Abstract: Diffusion walks take steps in the four directions N, E, S, and W. We derive a closed form for the number of diffusion walks from the origin to some point (n,n) on the diagonal in k steps inside the first octant, touching the diagonal exactly c times.
(Concerned with sequence A005558 .)
Received October 29 2004; revised version received September 1 2005; Published in Journal of Integer Sequences September 1 2005.