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 A271751 #19 Mar 03 2024 10:55:11
%S A271751 0,1,2,3,4,5,4,3,2,1,0,1,2,3,4,5,4,3,2,1,0,1,2,3,4,5,4,3,2,1,0,1,2,3,
%T A271751 4,5,4,3,2,1,0,1,2,3,4,5,4,3,2,1,0,1,2,3,4,5,4,3,2,1,0,1,2,3,4,5,4,3,
%U A271751 2,1,0,1,2,3,4,5,4,3,2,1,0,1,2,3,4,5
%N A271751 Period 10 zigzag sequence; repeat: [0, 1, 2, 3, 4, 5, 4, 3, 2, 1].
%C A271751 Decimal expansion of 11111/900009. - _Elmo R. Oliveira_, Mar 03 2024
%H A271751 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (1,0,0,0,-1,1).
%F A271751 G.f.: x*(1 + x + x^2 + x^3 + x^4)/(1 - x + x^5 - x^6).
%F A271751 a(n) = a(n-1) - a(n-5) + a(n-6) for n>5.
%F A271751 a(n) = abs(n - 10*round(n/10)).
%F A271751 a(n) = Sum_{i=1..n} (-1)^floor((i-1)/5).
%F A271751 a(2n) = 2*abs(A117444(n)).
%F A271751 a(2n+7) = 2*A076839(n)-1 for n>0.
%F A271751 a(n) = a(n-10) for n >= 10. - _Wesley Ivan Hurt_, Sep 07 2022
%p A271751 a:=n->[0, 1, 2, 3, 4, 5, 4, 3, 2, 1][(n mod 10)+1]: seq(a(n), n=0..100);
%t A271751 CoefficientList[Series[x*(1 + x + x^2 + x^3 + x^4)/(1 - x + x^5 - x^6), {x, 0, 30}], x]
%o A271751 (Magma) &cat[[0, 1, 2, 3, 4, 5, 4, 3, 2, 1]: n in [0..10]];
%o A271751 (PARI) a(n) = abs(n-10*round(n/10)); \\ _Altug Alkan_, Apr 13 2016
%Y A271751 Cf. A076839, A117444.
%Y A271751 Period k zigzag sequences: A000035 (k=2), A007877 (k=4), A260686 (k=6), A266313 (k=8), this sequence (k=10), A271832 (k=12), A279313 (k=14), A279319 (k=16), A158289 (k=18).
%K A271751 nonn,easy
%O A271751 0,3
%A A271751 _Wesley Ivan Hurt_, Apr 13 2016