Not entirely clear what you’re looking for here. If you want to produce a 1…N list for each symbol you can use til and avoid the sums and comparisons:
q)select 1+til count i by sym from t
sym | x
----| ---------------
aapl| 1 2 3 4 5
goog| 1 2 3 4 5 6 7 8
msft| 1 2 3 4 5 6 7
but it’s hard to see a use for the lists. Perhaps you simply want to count rows for each symbol?
q)exec count i by sym from t
aapl| 5
goog| 8
msft| 7
q)\ts:1000 select sums i=i by sym from t
4 10720
q)\ts:1000 exec count i by sym from t
1 9584
