Search: id:A085480
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%I A085480
%S A085480 3,15,54,207,783,2970,11259,42687,161838,613575,2326239,8819442,
%T A085480 33437043,126769455,480619494,1822166847,6908359023,26191577610,
%U A085480 99299809899,376474162527,1427321917278,5411388239415,20516130470079
%N A085480 a(n) = p^n + q^n, where p = (3 + sqrt 21)/2, q = (3 - sqrt 21)/2.
%C A085480 A Jacobsthal variation.
%C A085480 p - q = sqrt 21; pq = -3; p + q = 3.
%D A085480 Thomas Koshy, "Fibonacci and Lucas Numbers with Applications", Wiley, 
               2001, p. 471.
%H A085480 <a href="Sindx_Rea.html#recLCC">Index entries for sequences related to 
               linear recurrences with constant coefficients</a>
%H A085480 Tanya Khovanova, <a href="http://www.tanyakhovanova.com/RecursiveSequences/
               RecursiveSequences.html">Recursive Sequences</a>
%F A085480 a(n)=3*a(n-1)+3*a(n-2), a(1)=3, a(2)=15. G.f.: 3x*(1+2x)/(1-3x-3x^2). 
               [From Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Nov 19 2008]
%e A085480 a(4) = q^4 + q^4 = 207; p^5 + q^5 = 783, where p = (3 + sqrt 21)/2, q 
               = (3 - sqrt 21)/2.
%Y A085480 Cf. A030195.
%Y A085480 Sequence in context: A166035 A038192 A147618 this_sequence A099581 A026696 
               A082708
%Y A085480 Adjacent sequences: A085477 A085478 A085479 this_sequence A085481 A085482 
               A085483
%K A085480 nonn
%O A085480 1,1
%A A085480 Gary W. Adamson (qntmpkt(AT)yahoo.com), Jul 02 2003
%E A085480 More terms from Philippe DELEHAM (kolotoko(AT)wanadoo.fr), Sep 12 2009

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