postgres: generate series of timestamps respecting time zone - postgresql

Question

I'm stumped by a tricky issue regarding time zone changes from daylight savings to non daylight savings.
I'm trying to generate a series of timestamps, 6 hrs apart. This is later joined with data with corresponding timestamps at the 00, 06, 12, 18 hrs for each day in the dataset.
This works fine normally, using:
generate_series(extract(epoch from start_ts)::integer, extract(epoch from end_ts)::integer, 21600)
where start_ts is 00 hr on the first date, and end_ts is 00 hr on the last date exclusive.
However, when timezone offset goes from +11 to +10 half way through the series, it will no longer match any records since the series elements become 1 hr off.
Does anyone have suggestions on how to generate a series of 'epoch integers' or timestamps which would match 00,06,12,18 hr timestamps while respecting the timezone's offset?

Answer 1

This will generate it (using PostgreSQL 9.5+), starting from today and for 10 days:
select (current_date::timestamp + ((a-1)||' days')::interval)::timestamptz
from generate_series(1, 10, .25) a
Test it on a whole year:
select *, date_part('hour', d::timestamp), d::timestamp
from (
select (current_date::timestamp + ((a-1)||' days')::interval)::timestamptz AS d
from generate_series(1, 365, .25) a
) x
where date_part('hour', d) not in (0, 6, 12, 18)
Edit: The version below works with versions of PostgreSQL older than 9.5:
select (current_date::timestamp + (((a-1)/4.0)||' days')::interval)::timestamptz
from generate_series(1, 4* 10 ) a -- 10 days

Answer 2

#Ziggy's answer is great, use that. however here's how I solved it in my application which can't use decimals in generate_series (v9.4):
_min timestamp with time zone, -- the first timestamp in the series
_max timestamp with time zone, -- the last timestamp in the series
_inc integer, -- the increment in seconds, eg 21600 (6hr)
_tz text
creates a series from the _max down using the tz offset of the _max,
creates a series from the _min up using the tz offset of the _min,
merges the results
validates each result is divisible by the _inc in the tz of the result, discards if not
query:
select t1 from (
select ser,
to_timestamp(ser) t1,
extract(epoch from
to_timestamp(ser) at time zone _tz
- date_trunc('day', to_timestamp(ser) at time zone _tz)
)::integer % _inc = 0 is_good
from (
select 'ser1' s, generate_series(extract(epoch from _min)::integer, extract(epoch from _max)::integer, _inc) ser
union all
select 'ser2' s, generate_series(extract(epoch from _max)::integer, extract(epoch from _min)::integer, _inc * -1) ser
) x
group by ser, _tz, _inc
order by ser asc
) x
where is_good
;