OFFSET
0,2
LINKS
FORMULA
a(n) = (1-(-2)^n+3^n)/3 for n>0. a(n) = 2*a(n-1)+5*a(n-2)-6*a(n-3) for n>3. G.f.: 2*x*(1-x-x^2)/((1-x)*(1+2*x)*(1-3*x)). [Colin Barker, Sep 21 2012]
CROSSREFS
KEYWORD
nonn,walk,easy
AUTHOR
Paul Curtz, Jun 19 2008
EXTENSIONS
Edited and extended by R. J. Mathar, Aug 02 2008
STATUS
approved