OFFSET
1,1
COMMENTS
FORMULA
Conjecture: a(n) = 3*a(n-1)+3*a(n-2)-a(n-3). G.f.: x*(5+2*x-x^2)/((1+x)*(1-4*x+x^2)). [Colin Barker, Apr 08 2012]
CROSSREFS
KEYWORD
nonn
AUTHOR
Clark Kimberling, Sep 20 2011
STATUS
approved