At the moment I'm using this kind of sequence to provide a primary key
for some of my tables
create sequence group_seq;
select setval('group_seq', (select max(group_ID) from groups));
However I'd like to create a sequence that has this kind of output
g1
g2
g3
g4
g5
where g doesn't change
and
u1
u2
u3
where u doesn't change
is there are simple way of doing this?