creating names in plpgsql-functions

Hi,

is there a way to make a name in a plpgsql procedure dynamic? I want to
do something like this:

CREATE FUNCTION create_admin(BPCHAR)
RETURNS BPCHAR AS '
DECLARE
seqname name;
a alias for $1;
BEGIN
insert into admin(adminid)
values (a);

seqname := a || ''_seq'';

create sequence seqname;

return seqname;
END;'
LANGUAGE 'plpgsql';

Calling this function returns

SELECT create_admin('TS');
ERROR: parser: parse error at or near "$1"

Thanks,

Lieven