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 A131756 Period 3: repeat [2, -1, 3]. 1

%I

%S 2,-1,3,2,-1,3,2,-1,3,2,-1,3,2,-1,3,2,-1,3,2,-1,3,2,-1,3,2,-1,3,2,-1,

%T 3,2,-1,3,2,-1,3,2,-1,3,2,-1,3,2,-1,3,2,-1,3,2,-1,3,2,-1,3,2,-1,3,2,

%U -1,3,2,-1,3,2,-1,3,2,-1,3,2,-1,3,2,-1,3,2,-1,3,2,-1,3,2,-1,3,2,-1,3,2,-1,3,2,-1,3,2,-1,3,2,-1,3,2,-1,3,2,-1,3

%N Period 3: repeat [2, -1, 3].

%H <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,1).

%F a(n) = (1/9)*{7*(n mod 3)-8*[(n+1) mod 3]+13*[(n+3) mod 3]}. - _Paolo P. Lava_, Oct 08 2007

%F a(n) = 4/3+2/3*cos(2/3*Pi*n)-4/3*3^(1/2)*sin(2/3*Pi*n). - _R. J. Mathar_, Nov 15 2007

%F G.f.: (2-x+3*x^2)/(1-x^3). - _Jaume Oliver Lafont_, Mar 24 2009

%F a(n) = a(n-3) for n>2. - _Wesley Ivan Hurt_, Jul 01 2016

%p seq(op([2, -1, 3]), n=0..50); # _Wesley Ivan Hurt_, Jul 01 2016

%t PadRight[{}, 100, {2, -1, 3}] (* _Wesley Ivan Hurt_, Jul 01 2016 *)

%o (PARI) a(n)=[2,-1,3][1+n%3] \\ _Jaume Oliver Lafont_, Mar 24 2009

%o (MAGMA) &cat [[2, -1, 3]^^30]; // _Wesley Ivan Hurt_, Jul 01 2016

%Y Cf. A130784.

%K sign,easy

%O 0,1

%A _Paul Curtz_, Oct 04 2007

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Last modified February 17 18:46 EST 2019. Contains 320222 sequences. (Running on oeis4.)