user_tab_identity_cols / all_tab_identity_cols / dba_tab_identity_cols

select
   idc.table_name,
   idc.column_name,
   idc.generation_type,
   tac.default_on_null,
   idc.sequence_name,
   tac.data_default,
   idc.identity_options
from
   user_tab_identity_cols idc  join
   user_tab_columns       tac on idc.table_name  = tac.table_name and
                                 idc.column_name = tac.column_name;