I am using zadoff-chu sequences for channel estimation,

i found that the most used sequences are with root values: 25, 29, 34 and the length of the sequence is 63. Since i have 60 users to estimate their channels, then i need 60 sequences.

Is it possible to use additional roots other than 25, 29, 34, i.e. may i use 37,39, 41? is there any condition that the root value should satisfy?

Also for the cyclic shift, is there any limit for the number of cyclic shifts i can use ?

for the length of the sequence could it be like 24? and if so, would it affect the general formula for the sequence values?