This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A110569 #19 Dec 14 2023 05:18:08
%S A110569 2,1,3,3,1,2,2,1,3,3,1,2,2,1,3,3,1,2,2,1,3,3,1,2,2,1,3,3,1,2,2,1,3,3,
%T A110569 1,2,2,1,3,3,1,2,2,1,3,3,1,2,2,1,3,3,1,2,2,1,3,3,1,2,2,1,3,3,1,2,2,1,
%U A110569 3,3,1,2,2,1,3,3,1,2,2,1,3,3,1,2,2,1,3,3,1,2
%N A110569 Period 6: repeat [2, 1, 3, 3, 1, 2].
%C A110569 Permutation of {1, 2, 3}, followed by its reversal, repeated.
%H A110569 <a href="/index/Rec#order_05">Index entries for linear recurrences with constant coefficients</a>, signature (1,-1,1,-1,1).
%F A110569 a(n) = 1+(A078008(n) mod 3).
%F A110569 G.f.: (2-x+4*x^2-x^3+2*x^4) / (1-x+x^2-x^3+x^4-x^5).
%F A110569 a(n) = a(n-1) - a(n-2) + a(n-3) - a(n-4) + a(n-5) for n>4.
%F A110569 a(n) = 2 + cos(2*Pi*n/3)/2 - sqrt(3)*sin(2*Pi*n/3)/2 - cos(Pi*n/3)/2 + sqrt(3)*sin(Pi*n/3)/6.
%F A110569 a(n) = a(n-6) for n>5. - _Wesley Ivan Hurt_, Jun 27 2016
%p A110569 A110569:=n->[2, 1, 3, 3, 1, 2][(n mod 6)+1]: seq(A110569(n), n=0..100); # _Wesley Ivan Hurt_, Jun 27 2016
%t A110569 PadRight[{}, 100, {2, 1, 3, 3, 1, 2}] (* _Wesley Ivan Hurt_, Jun 27 2016 *)
%o A110569 (Magma) &cat [[2, 1, 3, 3, 1, 2]^^30]; // _Wesley Ivan Hurt_, Jun 27 2016
%o A110569 (PARI) x='x+O('x^50); Vec((2-x+4*x^2-x^3+2*x^4)/(1-x+x^2-x^3+x^4-x^5)) \\ _G. C. Greubel_, Aug 31 2017
%Y A110569 Cf. A078008, A105198, A110549, A110550, A110551, A110568.
%K A110569 easy,nonn
%O A110569 0,1
%A A110569 _Paul Barry_, Jul 27 2005
%E A110569 Name changed by _Wesley Ivan Hurt_, Jun 27 2016