A Schoenberg 12-tone row is a permutation of the integers from 0 to 11. It is assumed the first element is 0 so there are 11! 12-tone rows. The unordered interval sequence is the 1st-order difference modulo 12 arranged into a sorted list.
REFERENCES
Ole Kirkeby, Interval Sequences In 12-Tone Rows, to be submitted to Online Journal of Integer Sequences.
There is only one unordered interval sequence whose sum is 12, and it contains all ones. One of the 36 that sums up to 2*12=24 is [1,1,1,1,1,1,1,1,1,2,2,11], and one of the 798 that sums up to 3*12=36 is [1,1,1,1,1,1,1,1,3,3,11,11].