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A133270 Groups of 4 numbers describing a sequence of Minor 7th chords by assigning numbers 1 to 12 to an octave. 4
1, 4, 8, 11, 4, 7, 11, 2, 8, 11, 3, 6, 11, 4, 6, 9, 4, 7, 11, 2, 7, 10, 2, 5, 11, 4, 6, 9, 2, 5, 9, 12, 8, 11, 3, 6, 11, 4, 6, 9, 3, 6, 10, 1, 6, 9, 1, 4, 11, 4, 6, 9, 4, 7, 11, 2, 6, 9, 1, 4, 9, 12, 4, 7, 4, 7, 11, 2, 7, 10, 2, 5, 11, 4, 6, 9, 2, 5, 9, 12, 7, 10, 2, 5, 10, 3, 5, 8, 2, 5, 9, 12, 5, 8 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

A sequence of blocks of 4 numbers by reading the partial sequence from the left as in A133269, but here the interval assignments are for a minor 7th at the 12 base tones, explicitly: 1-> {1, 4, 8, 11}, 2-> {2, 5, 9, 12}, 3-> {3, 6, 10, 1}, 4-> {4, 7, 11, 2}, 5-> {5, 8, 12, 3}, 6-> {6, 9, 1, 4}, 7-> {7, 10, 2, 5}, 8-> {8, 11, 3, 6}, 9-> {9, 12, 4, 7}, 10-> {10, 3, 5, 8}, 11-> {11, 4, 6, 9}, 12-> {12, 5, 7, 10}.

LINKS

Table of n, a(n) for n=1..94.

Wikipedia, Minor seventh chord

EXAMPLE

Comments from N. J. A. Sloane, Aug 27 2017: (Start)

Define 12 4-note musical chords c(1), ..., c(12) by

1-> {1, 4, 8, 11}, 2-> {2, 5, 9, 12}, 3-> {3, 6, 10, 1}, 4-> {4, 7, 11, 2}, 5-> {5, 8, 12, 3}, 6-> {6, 9, 1, 4}, 7-> {7, 10, 2, 5}, 8-> {8, 11, 3, 6}, 9-> {9, 12, 4, 7}, 10-> {10, 3, 5, 8}, 11-> {11, 4, 6, 9}, 12-> {12, 5, 7, 10}.

The sequence is a 4-column table starting with c(1) = {1, 4, 8, 11} = {a(1), a(2), a(3), a(4)} and then continuing by successively appending c(a(2)), c(a(3)), c(a(4)), c(a(5)), ...

The array begins:

1, 4, 8, 11,

4, 7, 11, 2,

8, 11, 3, 6,

11, 4, 6, 9,

4, 7, 11, 2,

7, 10, 2, 5,

11, 4, 6, 9,

2, 5, 9, 12,

8, 11, 3, 6,

11, 4, 6, 9,

3, 6, 10, 1,

...

(End)

MATHEMATICA

Clear[s, p] s[i_] = {i, If[i + 3 > 12, i - 7, i + 3], If[i + 7 > 12, i - 5, i + 7], If[i + 10 > 12, i - 2, i + 10]}; t[a_] := Flatten[s /@ a]; p[0] = {1}; p[1] = t[p[0]]; p[n_] := t[p[n - 1]]; p[4]

CROSSREFS

Cf. A133269.

Sequence in context: A316505 A293597 A131803 * A131517 A076689 A161867

Adjacent sequences:  A133267 A133268 A133269 * A133271 A133272 A133273

KEYWORD

nonn,easy,tabf

AUTHOR

Roger L. Bagula, Oct 16 2007

EXTENSIONS

Comments inserted for clarification - The Assoc. Eds. of the OEIS, Aug 29 2010

Edited by N. J. A. Sloane, Aug 27 2017

STATUS

approved

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Last modified September 16 08:50 EDT 2019. Contains 327091 sequences. (Running on oeis4.)