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%I #24 Feb 13 2024 03:36:08
%S 2,19,181,1729,16561,159049,1531441,14782969,143046721,1387420489,
%T 13486784401,131381059609,1282429536481,12541865828329,
%U 122876792454961,1205891132094649,11853020188851841
%N a(n) = 9^n + 10^n.
%H Vincenzo Librandi, <a href="/A221904/b221904.txt">Table of n, a(n) for n = 0..1000</a>
%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (19,-90).
%F G.f.: 1/(1 - 9*x) + 1/(1 - 10*x).
%F E.g.f.: exp(9*x) + exp(10*x).
%F a(n) = 19*a(n-1) - 90*a(n-2), a(1)=2, a(2)=19.
%t CoefficientList[Series[1/(1-9*x) + 1/(1-10*x), {x, 0, 30}], x]
%t LinearRecurrence[{19,-90},{2,19},30] (* _Harvey P. Dale_, Nov 10 2017 *)
%o (Magma) [9^n + 10^n: n in [0..30]];
%Y Cf. A007689, A074611, A074615, A074619, A074622, A074624, A155872.
%K nonn,easy
%O 0,1
%A _Vincenzo Librandi_, Feb 06 2013
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