Unable to drop sequence due to dependency?

I can't drop a sequence. I get the error "cannot drop sequence
<sequence name> because other objects depend on it". I've tried to use
the pg_depend table to find out what object(s) depend on it, and have
found nothing.

I tried drop cascade in a transaction, hoping to see a list of objects
dropped in the cascade, but only got "DROP SEQUENCE".

I tried these two queries:

select * from pg_depend where objid = 1011680210;
select * from pg_depend where refobjid = 1011680210;

The first one returned one row with refobjid = 2200. That's a
namespace, so this appears to be the reverse of what I want.

The second one returned two rows with objid = 1011687585 and 1011680211;
OID 1011680211 is the type (in pg_type) that matches this sequence,
so this also appears to be the opposite of what I want. I couldn't find
OID 1011687585 anywhere.

Any hints? What type of objects can depend on a sequence? How can I
find out which ones depend on this particular one?

SELECT version()...
PostgreSQL 8.1.4 on x86_64-redhat-linux-gnu, compiled by GCC
x86_64-redhat-linux-gcc (GCC) 4.1.0 20060304 (Red Hat 4.1.0-3)

Thanks!

-Glen