%I
%S 1,2,2,10,2,38,46,106,290,134,1294,758,4418,7450,10222,40022,
%T 866,160954,157490,486326,1116286,829018,5294162,1978090,
%U 19198558,27110918,49683314,158126986,40606270,673114214,510689134,2181767722,4224524258
%N a(n) = a(n1)  4*a(n2), a(0)=1, a(1)=2.
%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (1,4).
%F G.f.: (1+x)/(1x+4*x^2).
%F a(n) = Sum_{k0..n} A133607(n,k)*2^k.  _Philippe Deléham_, Dec 29 2007
%F a(n) = (1/10)*i*sqrt(15)*(1/2  (1/2)*i*sqrt(15))^n  (1/10)*i*sqrt(15)*(1/2 + (1/2)*i*sqrt(15))^n + (1/2)*(1/2  (1/2)*i*sqrt(15))^n + (1/2)*(1/2 + (1/2)*i*sqrt(15))^n, with n >= 0 and i = sqrt(1).  _Paolo P. Lava_, Nov 18 2008
%K easy,sign
%O 0,2
%A _Philippe Deléham_, Dec 28 2007
