OFFSET
1,1
COMMENTS
This sequence uses nine basic tones with {2}->Bb as a terminator. If the triad chords are used only it has less of a blue sound and only has nine tones. It also goes from 4!=24 permutations possible to 3!=6: that significantly lowers the possible out comes for automated output. Substitutions with the permutations increase the variability of this type of sequence.
FORMULA
Substitution function that skip {6,10} and use {2} as a terminator:
s[1] = {12, 9, 5, 1};
s[2] = {2};
s[3] = {11, 7, 3, 2};
s[4] = {12, 8, 4, 3};
s[5] = Permutations[s[1]][[12]];
s[6] = {6};
s[7] = Permutations[s[3]][[12]]; s[8] = Permutations[s[4]][[12]];
s[9] = Permutations[s[1]][[23]];
s[10] = {10};
s[11] = Permutations[s[3]][[23]];
s[12] = Permutations[s[4]][[23]];
Permutations {12,23} are used for spread, but any two combinations of 24:Binomial[24,2]=46 can be used if the first substitutions are the reference state.
MATHEMATICA
Clear[s]
s[1] = {12, 9, 5, 1};
s[2] = {2};
s[3] = {11, 7, 3, 2};
s[4] = {12, 8, 4, 3};
s[5] = Permutations[s[1]][[12]];
s[6] = {6};
s[7] = Permutations[s[3]][[12]]; s[8] = Permutations[s[4]][[12]];
s[9] = Permutations[s[1]][[23]];
s[10] = {10};
s[11] = Permutations[s[3]][[23]];
s[12] = Permutations[s[4]][[23]];
t[a_] := Flatten[s /@ a]; p[0] = {1, 3, 4}; p[1] = t[p[0]];
p[n_] := t[p[n - 1]];
p[3]
CROSSREFS
KEYWORD
nonn,uned
AUTHOR
Roger L. Bagula, Nov 08 2007, Nov 09 2007
STATUS
approved