A159035 - OEIS

%I #4 May 02 2013 00:44:35

%S 1,1,2,5,14,40,114,324,920,2612,7416,21056,59784,169744,481952,

%T 1368400,3885280,11031424,31321376,88930368,252498816,716916544,

%U 2035531648,5779458048,16409538688,46591385856,132286304768,375598753024

%N a(0)=1=a(1), a(2)=2, a(3)=5; thereafter a(n+3)=4*a(n+2)-4*a(n+1)+2*a(n) for n>=1.

%C A117189 prefixed by an initial 1; essentially a duplicate. - _N. J. A. Sloane_ and _R. J. Mathar_, Apr 07 2009

%F G.f.: f(z)=((1-3*z+2*z^2-z^3)/(1-4*z+4*z^2-2*z^3))

%K easy,nonn

%O 0,3

%A _Richard Choulet_, Apr 03 2009