OFFSET
0,2
COMMENTS
lim_{n -> infinity} a(n)/a(n-1) = -4. [From Klaus Brockhaus, Sep 26 2009]
FORMULA
G.f.: (1+7x)/(1+3x-4x^2). a(n)= Sum_{k, 0<=k<=n} A112555(n,k)*3^(n-k). a(0)=1, a(1)=4, a(n)=4*a(n-2)-3*a(n-1).
a(n) = (8-3*(-4)^n)/5. [From Klaus Brockhaus and Paolo P. Lava, Sep 26 2009]
MATHEMATICA
NestList[8-4#&, 1, 30] (* Harvey P. Dale, Jul 11 2015 *)
CROSSREFS
KEYWORD
easy,sign
AUTHOR
Philippe Deléham, Sep 22 2009
EXTENSIONS
Corrected and extended by Harvey P. Dale, Jul 11 2015
STATUS
approved