OFFSET
1,2
LINKS
S. Gao and H. Niederhausen, Sequences Arising From Prudent Self-Avoiding Walks, 2010.
FORMULA
G.f.: x*(1+x-2*x^2+2*x^3)/(1-2*x-x^2+2*x^3-2*x^4).
PROG
(PARI) my(x='x+O('x^35)); Vec(x*(1+x-2*x^2+2*x^3)/(1-2*x-x^2+2*x^3-2*x^4)) \\ Michel Marcus, Jun 28 2021
CROSSREFS
KEYWORD
nonn,walk
AUTHOR
Shanzhen Gao, May 12 2011
STATUS
approved