cp's OEIS Frontend

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.

A083031 Numbers that are congruent to {0, 3, 7} mod 12.

Original entry on oeis.org

0, 3, 7, 12, 15, 19, 24, 27, 31, 36, 39, 43, 48, 51, 55, 60, 63, 67, 72, 75, 79, 84, 87, 91, 96, 99, 103, 108, 111, 115, 120, 123, 127, 132, 135, 139, 144, 147, 151, 156, 159, 163, 168, 171, 175, 180, 183, 187, 192, 195, 199, 204, 207, 211, 216, 219
Offset: 1

Views

Author

James Ingram (j.ingram(AT)t-online.de), Jun 01 2003

Keywords

Comments

Key-numbers of the pitches of a minor common chord on a standard chromatic keyboard, with root = 0.

Crossrefs

A guide for some sequences related to modes and chords:
Modes:
Lydian mode (F): A083089
Ionian mode (C): A083026
Mixolydian mode (G): A083120
Dorian mode (D): A083033
Aeolian mode (A): A060107 (raised seventh: A083028)
Phrygian mode (E): A083034
Locrian mode (B): A082977
Chords:
Major chord: A083030
Minor chord: this sequence
Dominant seventh chord: A083032

Programs

  • Magma
    [n : n in [0..300] | n mod 12 in [0, 3, 7]]; // Wesley Ivan Hurt, Jun 14 2016
    
  • Maple
    A083031:=n->(12*n-14-cos(2*n*Pi/3)+sqrt(3)*sin(2*n*Pi/3))/3: seq(A083031(n), n=1..100); # Wesley Ivan Hurt, Jun 14 2016
  • Mathematica
    Select[Range[0, 400], MemberQ[{0, 3, 7}, Mod[#, 12]] &] (* Wesley Ivan Hurt, Jun 14 2016 *)
    LinearRecurrence[{1, 0, 1, -1}, {0, 3, 7, 12}, 100] (* Jianing Song, Sep 22 2018 *)
  • PARI
    x='x+O('x^99); concat(0, Vec(x^2*(3+4*x+5*x^2)/((1+x+x^2)*(1-x)^2))) \\ Jianing Song, Sep 22 2018

Formula

G.f.: x^2*(3 + 4*x + 5*x^2)/((1 + x + x^2)*(1 - x)^2). - R. J. Mathar, Oct 08 2011
From Wesley Ivan Hurt, Jun 14 2016: (Start)
a(n) = a(n-1) + a(n-3) - a(n-4) for n > 4.
a(n) = (12*n - 14 - cos(2*n*Pi/3) + sqrt(3)*sin(2*n*Pi/3))/3.
a(3k) = 12k - 5, a(3k-1) = 12k - 9, a(3k-2) = 12k - 12. (End)
a(n) = a(n-3) + 12 for n > 3. - Jianing Song, Sep 22 2018