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 A217515 #24 Oct 13 2022 12:11:27
%S A217515 6,4,3,6,4,3,6,4,3,6,4,3,6,4,3,6,4,3,6,4,3,6,4,3,6,4,3,6,4,3,6,4,3,6,
%T A217515 4,3,6,4,3,6,4,3,6,4,3,6,4,3,6,4,3,6,4,3,6,4,3,6,4,3,6,4,3,6,4,3,6,4,
%U A217515 3,6,4,3,6,4,3,6,4,3,6,4,3,6,4,3,6,4,3,6,4,3,6
%N A217515 Base-n state complexity of partitioned deterministic finite automaton (PDFA) for the periodic sequence (123)*.
%H A217515 Klaus Sutner and Sam Tetruashvili, <a href="http://www.cs.cmu.edu/~sutner/papers/auto-seq.pdf">Inferring automatic sequences</a>.
%H A217515 <a href="/index/Rec#order_03">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,1).
%F A217515 Periodic with period length 3.
%F A217515 G.f.: x^2*(6 + 4*x + 3*x^2)/((1 - x^3)). - _Vincenzo Librandi_, Nov 18 2012
%t A217515 CoefficientList[Series[(6 + 4*x + 3*x^2)/((1 - x^3)),{x, 0, 40}], x] (* _Vincenzo Librandi_, Nov 18 2012 *)
%o A217515 (Magma) &cat[[6, 4, 3]: n in [0..30]]; // _Vincenzo Librandi_, Nov 18 2012
%K A217515 nonn,easy
%O A217515 2,1
%A A217515 _N. J. A. Sloane_, Oct 07 2012
%E A217515 Terms corrected by _Vincenzo Librandi_, Nov 18 2012