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%I #28 Dec 23 2023 08:37:08
%S -5,6,7,20,47,114,275,664,1603,3870,9343,22556,54455,131466,317387,
%T 766240,1849867,4465974,10781815,26029604,62841023,151711650,
%U 366264323,884240296,2134744915,5153730126,12442205167,30038140460,72518486087,175075112634
%N a(0)=-5, a(1)=6; thereafter a(n) = 2*a(n-1) + a(n-2).
%H Reinhard Zumkeller, <a href="/A221175/b221175.txt">Table of n, a(n) for n = 0..1000</a>
%H José L. Ramírez, Gustavo N. Rubiano, and Rodrigo de Castro, <a href="http://arxiv.org/abs/1212.1368">A Generalization of the Fibonacci Word Fractal and the Fibonacci Snowflake</a>, arXiv preprint arXiv:1212.1368 [cs.DM], 2012-2014.
%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (2,1).
%F a(n) = 16*A000129(n)-5*A000129(n+1). - _R. J. Mathar_, Jan 14 2013
%F G.f.: -(16*x-5) / (x^2+2*x-1). - _Colin Barker_, Jul 10 2015
%o (Haskell)
%o a221175 n = a221175_list !! n
%o a221175_list = -5 : 6 : zipWith (+)
%o (map (* 2) $ tail a221175_list) a221175_list
%o -- _Reinhard Zumkeller_, Jan 04 2013
%o (PARI) Vec(-(16*x-5)/(x^2+2*x-1) + O(x^50)) \\ _Colin Barker_, Jul 10 2015
%Y Cf. A000129, A078343, A221172, A221173, A221174.
%K sign,easy
%O 0,1
%A _N. J. A. Sloane_, Jan 04 2013
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