As is, the query (copied above) has false negatives in the case where oid values happen to collide across different pg_depend.classid values.
Fixed version:
selectns.nspnameasschema_name,seq.relnameasseq_namefrompg_classasseqjoinpg_namespacenson(seq.relnamespace=ns.oid)whereseq.relkind='S'andnotexists(select*frompg_dependwhereobjid=seq.oidanddeptype='a' and classid = 'pg_class'::regclass)orderbyseq.relname;