Many excellent designs for a new banner were submitted. We will use the best of them in rotation.
0,2
a(n)/a(n-1) tends to -3.
Table of n, a(n) for n=0..26.
G.f.: (1+4x)/(1+x-6x^2). a(n)= Sum_{k, 0<=k<=n}A112555(n,k)*2^k.
a(n) = (6*2^n-(-3)^n)/5. [From Klaus Brockhaus, Sep 26 2009]
Sequence in context: A131943 A100371 A100347 * A179857 A163590 A114320
Adjacent sequences: A165402 A165403 A165404 * A165406 A165407 A165408
sign
Philippe Deléham, Sep 17 2009
approved
