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 A154815 #15 Mar 15 2024 02:22:54
%S A154815 8,7,4,5,2,1,8,7,4,5,2,1,8,7,4,5,2,1,8,7,4,5,2,1,8,7,4,5,2,1,8,7,4,5,
%T A154815 2,1,8,7,4,5,2,1,8,7,4,5,2,1,8,7,4,5,2,1,8,7,4,5,2,1,8,7,4,5,2,1,8,7,
%U A154815 4,5,2,1,8,7,4,5,2,1,8,7,4,5,2,1,8,7
%N A154815 Period 6: repeat [8, 7, 4, 5, 2, 1].
%C A154815 Obtained through reversion of the period in A153990, or by taking a half period of A154811.
%C A154815 Shares digits with other 6-periodic sequences, see the list in A153130.
%C A154815 Also the decimal expansion of the constant 97169/111111. [_R. J. Mathar_, Jan 23 2009]
%H A154815 <a href="/index/Rec#order_06">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,0,0,1).
%F A154815 a(n) = (8*A153990(n)) mod 9.
%F A154815 G.f.: (8+7*x+4*x^2+5*x^3+2*x^4+x^5)/((1-x)*(1+x)*(1+x+x^2)(x^2-x+1)). [_R. J. Mathar_, Jan 23 2009]
%F A154815 From _Wesley Ivan Hurt_, Jun 23 2016: (Start)
%F A154815 a(n) = a(n-6) for n>5.
%F A154815 a(n) = (27 + cos(n*Pi) + 8*cos(n*Pi/3) + 12*cos(2*n*Pi/3) + 8*sqrt(3)*sin(n*Pi/3) + 4*sqrt(3)*sin(2*n*Pi/3))/6. (End)
%p A154815 A154815:=n->[8, 7, 4, 5, 2, 1][(n mod 6)+1]: seq(A154815(n), n=0..100); # _Wesley Ivan Hurt_, Jun 23 2016
%t A154815 PadRight[{}, 100, {8, 7, 4, 5, 2, 1}] (* _Wesley Ivan Hurt_, Jun 23 2016 *)
%o A154815 (Magma) &cat [[8, 7, 4, 5, 2, 1]^^20]; // _Wesley Ivan Hurt_, Jun 23 2016
%Y A154815 Cf. A153130, A153990, A154811.
%K A154815 nonn,easy
%O A154815 0,1
%A A154815 _Paul Curtz_, Jan 15 2009
%E A154815 Edited by _R. J. Mathar_, Jan 23 2009