So there are several ways to approach this, but your data set is missing necessary information for creating a date variable. You can easily convert these, but you have data that lists five weeks, and then repeats the same weeks, which leads me to the following questions about your data: Are there by variables? Do you know the year? Are these repeated observations for the same set of weeks, or are these different years or just by groups?
You could also use seasonality=5 on the proc statement, which would tell it that there is a seasonality of 5, as you would guess, but I'm not sure how you're using PROC ESM or ARIMA without a date variable?
I have drafted a little bit of code that could help you, but I am making the assumption that the year is 2017 for all of your date variables and your data is not sorted by week, thus you have repeated observations. You will notice there will be a large gap in data if this spans multiple years since there are 52 weeks in a year and you only have five.
I added this code above your "datalines" statement
the first line will get the date for the Sunday of the given week, you then add the number of days to get the actual day. There might be a more sophisticated way to do this with multipliers and shifts, but this was the easiest. I added a format to show you the dates will give you the weekday as given. More information on this is given in the ETS doc chapter "Date Intervals, Formats, and Functions"
datestart=intnx('week','01JAN2017'd,week); actualdate=intnx('day',datestart,weekday-1); format datestart actualdate weekdate.;
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