OFFSET
1,2
COMMENTS
Previous name was: Seven-tone substitution on a Fano projective plane graph as used in A120714 (for use in making church tone A,B,C,D,E,F,G music).
Idea inspired by a post in yahoo egroup fractals by "Dahlia Lahla" astro_girl_690(AT)yahoo.ca
In Mathematica you can transfer this to a 12-tone MIDI scale as: to letters
b = a /. 1 -> "a" /. 2 -> "b" /. 3 -> "c" /. 4 -> "d" /. 5 -> "e" /. 6 -> "f" /. 7 -> "g"
back to numbers on a 12-tone scale:
c = b /. "a" -> 1 /. "b" -> 3 /. "c" -> 4 /. "d" -> 6 /. "e" -> 8 /. "f" -> 9 /. "g" -> 11
LINKS
Roger L. Bagula, Feb 26 2008, Table of n, a(n) for n = 1..314
MATHEMATICA
s[1] = {2, 6, 7}; s[2] = {1, 3, 4, 6, 7}; s[3] = {2, 4, 7}; s[4] = {2, 3, 5, 6, 7}; s[5] = {4, 6, 7}; s[6] = {1, 2, 4, 5, 7}; s[7] = {1, 2, 3, 4, 5, 6};
t[a_] := Flatten[s /@ a];
p[0] = s[1]; p[1] = t[p[0]]; p[n_] := t[p[n - 1]]; a = p[3]
CROSSREFS
KEYWORD
nonn,easy,less
AUTHOR
Roger L. Bagula, Feb 26 2008
EXTENSIONS
Edited and new name from Joerg Arndt, Sep 26 2018
STATUS
approved