%I #8 Feb 18 2016 14:34:15
%S 1,5,37,317,2821,25325,227797,2049917,18448741,166037645,1494336757,
%T 13449026717,121041232261,1089371073965,9804339632917,88239056630717,
%U 794151509545381,7147363585646285,64326272270292277,578936450431581917
%N a(n) = (3^(2*n+1) + 2^(n+2))/7.
%C 3^(2*n+1) + 2^(n+2) = 3*(3^2)^n + 4*2^n == 3*2^n + 4*2^n = 7*2^n == 0 (mod 7).
%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (11,-18).
%F G.f.: ( 1-6*x ) / ( (9*x-1)*(2*x-1) ). - _R. J. Mathar_, Feb 18 2016
%e a(2) = (3^5 + 2^4)/7 = 259/7 = 37.
%p a:= n-> (3^(2*n+1) + 2^(n+2))/7:
%p seq (a(n), n=0..30);
%K nonn,easy
%O 0,2
%A _Michel Lagneau_, Apr 26 2010
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