%I #17 Jul 30 2015 17:31:44
%S 0,9,9,18,27,45,72,117,189,306,495,801,1296,2097,3393,5490,8883,14373,
%T 23256,37629,60885,98514,159399,257913,417312,675225,1092537,1767762,
%U 2860299,4628061,7488360,12116421,19604781,31721202,51325983,83047185,134373168
%N Fibonacci sequence beginning 0, 9.
%D A. T. Benjamin and J. J. Quinn, Proofs that really count: the art of combinatorial proof, M.A.A. 2003, p. 15.
%H Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/RecursiveSequences.html">Recursive Sequences</a>
%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (1, 1).
%F a(n) = round( (18phi-9)/5 phi^n) (works for n>4) - _Thomas Baruchel_, Sep 08 2004
%F a(n) = 9F(n) = F(n+4) + F(n+1) + F(n-2) + F(n-4), n>3.
%F G.f.: 9*x/(1-x-x^2). - _Philippe Deléham_, Nov 20 2008
%t a={};b=0;c=9;AppendTo[a, b];AppendTo[a, c];Do[b=b+c;AppendTo[a, b];c=b+c;AppendTo[a, c], {n, 4!}];a (* _Vladimir Joseph Stephan Orlovsky_, Sep 17 2008 *)
%Y Cf. A000032.
%K nonn,easy
%O 0,2
%A _N. J. A. Sloane_.