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%I #44 Oct 12 2015 09:39:53
%S 2,10,58,370,2482,17050,118378,825730,5771362,40373290,282534298,
%T 1977503890,13841818642,96890604730,678227855818,4747575858850,
%U 33232973616322,232630643127370,1628413985330938,11398896347634610
%N a(n) = 3^n + 7^n.
%H G. C. Greubel and Jon E. Schoenfield, <a href="/A074608/b074608.txt">Table of n, a(n) for n = 0..1000</a> (terms 0..160 from G. C. Greubel).
%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (10,-21).
%F From _Mohammad K. Azarian_, Jan 11 2009: (Start)
%F G.f.: 1/(1-3*x) + 1/(1-7*x).
%F E.g.f.: exp(3*x) + exp(7*x). (End)
%F a(n) = 10*a(n-1)-21*a(n-2) with a(0)=2, a(1)=10. - _Vincenzo Librandi_, Jul 21 2010
%F a(n) = 2 * A081336(n). - _Michel Marcus_, Oct 07 2015
%t Table[3^n + 7^n, {n, 0, 25}]
%t RecurrenceTable[{a[0]== 2, a[1]== 10, a[n]== 10*a[n-1] - 21*a[n-2]}, a, {n,30}] (* _G. C. Greubel_, Aug 20 2015 *)
%o (PARI) first(m)=vector(m,i,i--;3^i + 7^i) \\ _Anders Hellström_, Aug 20 2015
%o (PARI) Vec(1/(1-3*x) + 1/(1-7*x) + O(x^50)) \\ _Altug Alkan_, Oct 12 2015
%Y Cf. A000051, A034472, A052539, A034474, A062394, A034491, A062395, A062396, A007689, A063376, A063481, A074600 - A074624.
%Y Cf. A081336.
%K easy,nonn
%O 0,1
%A _Robert G. Wilson v_, Aug 25 2002
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