And the wikipedia page https://en.wikipedia.org/wiki/Combinatorial_number_system.
If you want some more theoretical stuff, Knuth has a chapter about combinations that's easily googleable. Mark On 12 Sep 2016 03:01, "stef" <s...@ctrlc.hu> wrote: > On Mon, Sep 12, 2016 at 11:09:06AM +1000, James A. Donald wrote: > > I need to be able to do two of the following three tasks. > > > > Generate a permutation of eighteen ones and eighteen zeros with equal > > probability for each permutation. Or equivalently shuffle eighteen black > > cards and eighteen red cards. > > > > Sequentially generate all possible permutations with each permutation > > generated once and only once. > > > > Map between permutations and scalars, such that each permutation maps to > > unique number, and the set of numbers that represents valid permutations > is > > dense. > > > > Could someone point me to the relevant literature, or literature for > > converting between different representations of a permutation? > > > > Since there are only two classes of items being shuffled, this class of > > permutations has a variety of special and convenient properties. > > https://stackoverflow.com/questions/1506078/fast-permutation-number- > permutation-mapping-algorithms > > > -- > otr fp: https://www.ctrlc.hu/~stef/otr.txt >