A ternary notation

[Eric Angelini]

> If you use 2 to represent the -1 digit, you will get:
> 0, 1, 12, 10, 11, 122, 120, 121, 102, 100, 101, ...

... This could be used to represent the natural numbers
with primes instead of powers of 3:

     2  3  5  7  11  13  17  19  23 ...

0=0              => 0
1=   2  1        => 21
2=   1           => 1
3=   0  1        => 10
4=   1  2  1     => 121
5=   1  1        => 11
6=   2  1  1     => 112
7=   1  0  1     => 101
8=   0  1  1     => 110
9=   1  0  0  1  => 1001
10=  1  1  1     => 111
11=  1  2  1  1  => 1121
12=  2  0  1  1  => 1102

etc.

best,
and thanks to all contributors,
É.