rolling forward, or backward?
one row per week or per day?
This will give you a starting point.
This shows a rolling 13 weeks in the past, not counting current week.
The SYS_CALENDAR.CALENDAR has the first day of the week as Sunday.
, C.WEEK_OF_CALENDAR - W.WEEK_OF_CALENDAR AS WEEKS_AGO
FROM SYS_CALENDAR.CALENDAR C
, (SELECT WEEK_OF_CALENDAR
WHERE CALENDAR_DATE = DATE) W
WHERE C.WEEK_OF_CALENDAR - W.WEEK_OF_CALENDAR BETWEEN -13 AND -1
ORDER BY 1