OFFSET
0,2
COMMENTS
The number of walks ending with x = -k is the same as the number ending with x = k.
LINKS
Bert Dobbelaere, Table of n, a(n) for n = 0..275 (terms 0..152 from Joseph Myers)
J. L. Martin, The exact enumeration of self-avoiding walks on a lattice, Proc. Camb. Phil. Soc., 58 (1962), 92-101.
FORMULA
For n > 0, A001412(n) = T(n,0) + 2 * Sum_{k=1..n} T(n,k). - Bert Dobbelaere, Jan 06 2019
EXAMPLE
Initial rows (paths of length 0, 1, 2, ...):
1;
4, 1;
12, 8, 1;
44, 40, 12, 1;
...
CROSSREFS
KEYWORD
AUTHOR
Joseph Myers, Jul 07 2013
STATUS
approved