probabil ca te referi la prefixurile utilizate la definirea nr. at de C dintr_o catena....
1 = met
2 = et
3 = prop
4 = but
5 = pent
6 = hex
7 = hept
8 = oct
9 = non
10 = dec
11 = und
12 = dod
13 = tridec
14 = tatradec
15 = pentadec
16 = hexadec
17 = heptadec
18 = octadec
19 = nonadec
20 = eicos
.................