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%I #14 Feb 20 2019 21:15:35
%S 11,90,372,1512,6096,24480,98112,392832,1572096,6289920,25162752,
%T 100657152,402640896,1610588160,6442401792,25769705472,103079018496,
%U 412316467200,1649266655232,6597068193792,26388275920896
%N a(n) = 6*a(n-1) - 8*a(n-2) for n > 2; a(0) = 11, a(1) = 90, a(2) = 372.
%C Related to Reverse and Add trajectory of 22 in base 2: A061561(4*n) = 2*a(n).
%C Binary representation of a(n) for n > 0 is given by the following production rules of the contextfree grammar: S -> 101 T 0, T -> 1 T 0 | 101. - _A.H.M. Smeets_, Feb 11 2019
%H Vincenzo Librandi, <a href="/A171470/b171470.txt">Table of n, a(n) for n = 0..500</a>
%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (6,-8).
%F a(n) = 24*4^n-3*2^n for n > 0.
%F G.f.: (1+4*x)*(11-20*x)/((1-2*x)*(1-4*x)).
%o (PARI) {m=21; v=concat([11, 90, 372], vector(m-3)); for(n=4, m, v[n]=6*v[n-1]-8*v[n-2]); v}
%Y Cf. A061561, A171471, A171472, A171473.
%K nonn,easy
%O 0,1
%A _Klaus Brockhaus_, Dec 09 2009
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