All the oracle sequences are stored in a table called "dba_sequences".

The following query selects the min, max ,current value along with the length current value and orders it by the length in desc.

select SEQUENCE_NAME,MIN_VALUE,MAX_value,LAST_NUMBER,length(LAST_NUMBER)

from dba_sequences

where SEQUENCE_OWNER='schema owner'

order by length(LAST_NUMBER)desc;