A374298 Number of growing self-avoiding walks with displacement n on a half-infinite strip of height 3 with a trapped endpoint.

2, 10, 40, 148, 526, 1828, 6256, 21190, 71260, 238432, 794914, 2643352, 8773684, 29082010, 96303640, 318678388, 1053993646, 3484654468, 11517602176, 38060746390, 125756057260, 415464635392, 1372477613794, 4533688494712, 14975452784164, 49464657237610

Offset: 1

Author

Jay Pantone, Jul 03 2024

Keywords

• nonn

Comments

A growing self-avoiding walk (GSAW) is a walk on a graph that is directed, does not visit the same vertex twice, and for which all neighbors of the endpoint are part of the walk, i.e., the endpoint is trapped. This sequence is about GSAWs on the grid graph of integer points (x,y) where x >= 0 and y is in {0,1,2}. The GSAW must start at the point (0,0). The displacement of a GSAW is the difference between the largest and smallext x-values that it reaches.

Examples

			The a(1) = 2 walks are:
  *--*  *      *--*  *
     |         |  |
  *--*  *      *  *  *
  |               |
  *  *  *      *--*  *
		

Links

• Jay Pantone, A. R. Klotz, and E. Sullivan, Exactly-solvable self-trapping lattice walks. II. Lattices of arbitrary height., arXiv:2407.18205 [math.CO], 2024.

Crossrefs

Cf. A078528, A374297.

Formula

G.f.: (-2*x*(x+1)*(x^3+x-1))/((x^2+2*x-1)*(x^2+3*x-1)).