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%I #31 Dec 14 2023 06:05:30
%S 5,7,5,7,5,7,5,7,5,7,5,7,5,7,5,7,5,7,5,7,5,7,5,7,5,7,5,7,5,7,5,7,5,7,
%T 5,7,5,7,5,7,5,7,5,7,5,7,5,7,5,7,5,7,5,7,5,7,5,7,5,7,5,7,5,7,5,7,5,7,
%U 5,7,5,7,5,7,5,7,5,7,5,7,5
%N Periodic sequence: repeat [5, 7].
%C Also continued fraction expansion of (35 + sqrt(1365))/14. - _Bruno Berselli_, Sep 29 2011
%H <a href="/index/Rec#order_02">Index entries for linear recurrences with constant coefficients</a>, signature (0,1).
%F From _Paolo P. Lava_, Oct 20 2006: (Start)
%F a(n) = (-1)^(n+1) + 6.
%F (End)
%F From _Vincenzo Librandi_, Aug 01 2010: (Start)
%F a(n) = a(n-2) for n > 1, with a(0)=5, a(1)=7.
%F G.f.: (5+7*x)/((1-x)*(1+x)). (End)
%p seq(op([5, 7]), n=0..100); # _Wesley Ivan Hurt_, Dec 26 2016
%t (-1)^(Range[0, 100] + 1) + 6 (* _Wesley Ivan Hurt_, Dec 26 2016 *)
%o (Magma) &cat [[5, 7]^^50]; // _Wesley Ivan Hurt_, Dec 26 2016
%o (PARI) for(n=0,20, print1((-1)^(n+1) + 6, ", ")) \\ _G. C. Greubel_, Dec 26 2016
%o (Python)
%o def A010718(n): return 5 + 2*(n & 1) # _Chai Wah Wu_, May 25 2022
%K nonn,easy
%O 0,1
%A _N. J. A. Sloane_
%E Definition rewritten by _Bruno Berselli_, Sep 29 2011
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