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 A173598 #27 Dec 12 2023 07:39:04
%S A173598 1,8,7,2,4,5,1,8,7,2,4,5,1,8,7,2,4,5,1,8,7,2,4,5,1,8,7,2,4,5,1,8,7,2,
%T A173598 4,5,1,8,7,2,4,5,1,8,7,2,4,5,1,8,7,2,4,5,1,8,7,2,4,5,1,8,7,2,4,5,1,8,
%U A173598 7,2,4,5,1,8,7,2,4,5,1,8,7,2,4,5,1,8
%N A173598 Period 6: repeat [1, 8, 7, 2, 4, 5].
%C A173598 For A141425 = 1,2,4,5,7,8 permutations, see A153130. a(n) is based on A022998. Successive differences are linked to A070366.
%H A173598 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,0,0,1).
%F A173598 a(n) = A166138(n) mod 9.
%F A173598 a(2n+1) + a(2n+2) = 9.
%F A173598 G.f.: (1+8*x+7*x^2+2*x^3+4*x^4+5*x^5) / ((1-x)*(1+x)*(1+x+x^2)*(x^2-x+1)). - _R. J. Mathar_, Mar 08 2011
%F A173598 From _Wesley Ivan Hurt_, Jun 23 2016: (Start)
%F A173598 a(n) = a(n-6) for n>5.
%F A173598 a(n) = (9 - cos(n*Pi) - 6*cos(2*n*Pi/3) + 2*sqrt(3)*sin(n*Pi/3))/2. (End)
%p A173598 A173598:=n->[1, 8, 7, 2, 4, 5][(n mod 6)+1]: seq(A173598(n), n=0..100); # _Wesley Ivan Hurt_, Jun 23 2016
%t A173598 PadRight[{}, 100, {1, 8, 7, 2, 4, 5}] (* _Wesley Ivan Hurt_, Jun 23 2016 *)
%o A173598 (PARI) a(n)=[1,8,7,2,4,5][n%6+1] \\ _Charles R Greathouse IV_, Jun 02 2011
%o A173598 (Magma) &cat [[1, 8, 7, 2, 4, 5]^^20]; // _Wesley Ivan Hurt_, Jun 23 2016
%Y A173598 Cf. A022998, A070366, A141425, A153130, A166138.
%K A173598 nonn,easy
%O A173598 0,2
%A A173598 _Paul Curtz_, Nov 23 2010