OFFSET
0,2
COMMENTS
a(n) is also the first entry of the vector M^n*[1,0,0,0], where M is the type F_4 Cartan matrix [[2,-1,0,0]; [ -1,2,-2,0]; [0,-1,2,-1]; [0,0,-1,2]].
FORMULA
G.f.: -(2*x-1)*(x^2-4*x+1)/(1-8*x+20*x^2-16*x^3+x^4). - R. J. Mathar, Nov 14 2007
MATHEMATICA
a = {1, 2, 5, 14}; Do[AppendTo[a, 8*a[[ -1]]-20*a[[ -2]]+16*a[[ -3]]-a[[ -4]]], {24}]; a
CROSSREFS
KEYWORD
nonn
AUTHOR
Gary W. Adamson, Dec 28 2006
EXTENSIONS
Edited and extended by Stefan Steinerberger, Aug 12 2007
STATUS
approved