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%I #30 Mar 28 2024 13:18:58
%S 11,23,71,263,1031,4103,16391,65543,262151,1048583,4194311,16777223,
%T 67108871,268435463,1073741831,4294967303,17179869191,68719476743,
%U 274877906951,1099511627783,4398046511111,17592186044423,70368744177671,281474976710663
%N a(n) = 4^(n+1) + 7.
%C These are the even terms of A168415. Since the odd terms of A168415 are divisible by three the primes of this sequence are the same as A104066.
%H Vincenzo Librandi, <a href="/A195463/b195463.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 (5,-4).
%F a(n) = 4^(n+1) + 7.
%F From _Alexander R. Povolotsky_, Sep 19 2011: (Start)
%F G.f.: (11 - 32*x)/(1 - 5*x + 4*x^2).
%F a(n+1) = 4*a(n) - 21. (End)
%F a(n) = A188165(2n+2) - 2. - _Bruno Berselli_, Sep 26 2011
%o (PARI) a(n)=4^(n+1)+7 \\ _Charles R Greathouse IV_, Sep 19 2011
%o (Magma) [4^(n+1) + 7: n in [0..30]]; // _Vincenzo Librandi_, Sep 30 2011
%Y Cf. A168415, A104066.
%K nonn,easy
%O 0,1
%A _Brad Clardy_, Sep 19 2011
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