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 A258054 #35 Mar 17 2023 09:54:43
%S A258054 1,6,11,4,9,2,7,12,5,10,3,8,1,6,11,4,9,2,7,12,5,10,3,8,1,6,11,4,9,2,7,
%T A258054 12,5,10,3,8,1,6,11,4,9,2,7,12,5,10,3,8,1,6,11,4,9,2,7,12,5,10,3,8,1,
%U A258054 6,11,4,9,2,7,12,5,10,3,8,1,6,11,4,9,2,7,12,5,10,3,8,1,6,11,4,9,2,7,12,5,10,3,8,1,6,11,4,9,2,7,12,5,10,3,8
%N A258054 Circle of fifths cycle (counterclockwise).
%C A258054 The twelve notes dividing the octave are numbered 1 through 12 sequentially. This sequence begins at a certain note, travels down a perfect fifth twelve times (seven semitones), and arrives back at the same note. If justly tuned fifths are used, the final note will be flat by the Pythagorean comma (roughly 23.46 cents or about a quarter of a semitone).
%C A258054 Period 12: repeat [1, 6, 11, 4, 9, 2, 7, 12, 5, 10, 3, 8]. - _Omar E. Pol_, May 18 2015
%C A258054 The string [1, 6, 11, 4, 9, 2, 7, 12, 5, 10, 3, 8] is also in both A023127 and A054073. - _Omar E. Pol_, May 19 2015
%H A258054 OEIS Wiki, <a href="https://oeis.org/wiki/The_multi-faceted_reach_of_the_OEIS#Music">The multi-faceted reach of the OEIS: Music</a>
%H A258054 Wikipedia, <a href="http://en.wikipedia.org/wiki/Circle_of_fifths">Circle of fifths</a>
%H A258054 Wikipedia, <a href="http://en.wikipedia.org/wiki/Pythagorean_comma">Pythagorean comma</a>
%H A258054 <a href="/index/Rec#order_12">Index entries for linear recurrences with constant coefficients</a>, signature (0,0,0,0,0,0,0,0,0,0,0,1).
%H A258054 <a href="https://oeis.org/index/Mu#music">OEIS index entry for music</a>
%F A258054 Periodic with period 12: a(n) = 1 + (5(n-1) mod 12).
%F A258054 From _Colin Barker_, Nov 15 2019: (Start)
%F A258054 G.f.: x*(1 + 6*x + 11*x^2 + 4*x^3 + 9*x^4 + 2*x^5 + 7*x^6 + 12*x^7 + 5*x^8 + 10*x^9 + 3*x^10 + 8*x^11) / (1 - x^12).
%F A258054 a(n) = a(n-12) for n>12.
%F A258054 (End)
%e A258054 For a(3), 1+5+5 = 11 (mod 12).
%e A258054 For a(4), 1+5+5+5 = 4 (mod 12).
%p A258054 A258054:=n->1+(5*(n-1) mod 12): seq(A258054(n), n=1..100); # _Wesley Ivan Hurt_, May 22 2015
%t A258054 PadRight[{}, 100, {1, 6, 11, 4, 9, 2, 7, 12, 5, 10, 3, 8}] (* _Vincenzo Librandi_, May 19 2015 *)
%t A258054 LinearRecurrence[{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1},{1, 6, 11, 4, 9, 2, 7, 12, 5, 10, 3, 8},108] (* _Ray Chandler_, Aug 27 2015 *)
%o A258054 (Magma) [1+5*(n-1) mod 12: n in [1..80]]; // _Vincenzo Librandi_, May 19 2015
%o A258054 (PARI) a(n)=1+5*(n-1) \\ _Charles R Greathouse IV_, May 22 2015
%o A258054 (PARI) Vec(x*(1 + 6*x + 11*x^2 + 4*x^3 + 9*x^4 + 2*x^5 + 7*x^6 + 12*x^7 + 5*x^8 + 10*x^9 + 3*x^10 + 8*x^11) / (1 - x^12) + O(x^80)) \\ _Colin Barker_, Nov 15 2019
%Y A258054 Cf. A221363 (Pythagorean comma), A257811 (clockwise circle of fifths cycle).
%K A258054 nonn,easy
%O A258054 1,2
%A A258054 _Peter Woodward_, May 17 2015
%E A258054 Extended by _Ray Chandler_, Aug 27 2015