How to get list of sequence names in Postgres?

You can use:

select sequence_schema, sequence_name
from information_schema.sequences;

That will return a list of sequences accessible to the current user, not the ones owned by him.

If you want to list sequences owned by the current user you need to join pg_class, pg_namespace and pg_user:

select n.nspname as sequence_schema, 
       c.relname as sequence_name,
       u.usename as owner
from pg_class c 
  join pg_namespace n on n.oid = c.relnamespace
  join pg_user u on u.usesysid = c.relowner
where c.relkind = 'S'
  and u.usename = current_user;

In Postgres a user can own objects (e.g. sequences) in multiple schemas, not just "his own", so you also need to check in which schema the sequence is created.

More details in the manual:

• https://www.postgresql.org/docs/current/static/infoschema-sequences.html
• https://www.postgresql.org/docs/current/static/catalog-pg-class.html