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%I #42 Dec 14 2023 06:04:29
%S 4,7,4,7,4,7,4,7,4,7,4,7,4,7,4,7,4,7,4,7,4,7,4,7,4,7,4,7,4,7,4,7,4,7,
%T 4,7,4,7,4,7,4,7,4,7,4,7,4,7,4,7,4,7,4,7,4,7,4,7,4,7,4,7,4,7,4,7,4,7,
%U 4,7,4,7,4,7,4,7,4,7,4,7,4
%N Period 2: repeat (4,7).
%C a(n) = A047892(n+1) mod 9. - _Reinhard Zumkeller_, Sep 23 2007
%C Continued fraction expansion of A176217. - _R. J. Mathar_, Mar 08 2012
%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (0,1).
%F a(n) = -(3/2)*(-1)^n + 11/2. - _Paolo P. Lava_, Oct 20 2006
%F a(n) = 3 + 4^(n mod 2). - _Reinhard Zumkeller_, Sep 23 2007
%F G.f.: (4+7x)/((1-x)(1+x)). - _R. J. Mathar_, Nov 21 2011
%F a(n) = 4 + 2^(1-(-1)^n) - 1. - _Vincenzo Librandi_, Feb 27 2020
%t PadRight[{},120,{4,7}] (* _Harvey P. Dale_, Nov 15 2012 *)
%o (PARI) a(n)=4+n%2*3 \\ _Charles R Greathouse IV_, Dec 21 2011
%o (Haskell)
%o a010712 = (+ 3) . (4 ^) . flip mod 2
%o a010712_list = cycle [4, 7] -- _Reinhard Zumkeller_, Mar 19 2014
%o (Magma) &cat [[4, 7]^^50]; // _Vincenzo Librandi_, Feb 27 2020
%K nonn,easy
%O 0,1
%A _N. J. A. Sloane_
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