OFFSET
0,2
FORMULA
a(n) = 3*a(n-1)+3*a(n-2) = 21*A030195(n). G.f.: 21*x/(1-3*x-3*x^2). [From R. J. Mathar, Feb 05 2010]
EXAMPLE
G(n,0)=0 G(n,1)=n*(n+4)
CROSSREFS
KEYWORD
nonn
AUTHOR
Claudio Peruzzi (claudio.peruzzi(AT)gmail.com), Feb 04 2010
EXTENSIONS
More terms from R. J. Mathar, Feb 05 2010
STATUS
approved