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 A074611 4^n + 5^n. 3

%I

%S 2,9,41,189,881,4149,19721,94509,456161,2215269,10814201,53022429,

%T 260917841,1287811989,6371951081,31591319949,156882857921,

%U 780119322309,3883416742361,19348364235069,96466943268401,481235204714229

%N 4^n + 5^n.

%H Vincenzo Librandi, <a href="/A074611/b074611.txt">Table of n, a(n) for n = 0..1000</a>

%H <a href="/index/Rec">Index entries for linear recurrences with constant coefficients</a>, signature (9,-20).

%F G.f.: 1/(1-4*x)+1/(1-5*x). E.g.f.: e^(4*x)+e^(5*x). [_Mohammad K. Azarian_, Jan 11 2009]

%F a(n) = 9*a(n-1) - 20*a(n-2) with n>1, a(0)=2, a(1)=9. [_Vincenzo Librandi_, Jul 21 2010]

%t Table[4^n + 5^n, {n, 0, 25}]

%t CoefficientList[Series[1/(1 - 4 x) + 1/(1 - 5 x), {x, 0, 30}], x] (* _Vincenzo Librandi_, Feb 06 2013 *)

%o (MAGMA) [4^n + 5^n: n in [0..30]]; // _Vincenzo Librandi_, Feb 06 2013

%Y Cf. A000051, A034472, A052539, A034474, A062394, A034491, A062395, A062396, A007689, A063376, A063481, A074600 - A074624.

%K easy,nonn

%O 0,1

%A _Robert G. Wilson v_, Aug 25 2002

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Last modified April 23 13:25 EDT 2019. Contains 322386 sequences. (Running on oeis4.)