Thanks to be informed that ,
For cable sizes in capacitor banks, we recommend using the table on page 42 of the PanelBuilders Guide. I've attached the guide for your reference.
It is better to use the table then the formula that you have provided. The difference between the table and your proposed formula is that the table is calculated at 1.5 times the related current of capacitor whereas the formula you proposed only takes it at 1.35. User will not save much, in terms of cost, by applying factor of 1.35 instead of 1.5. But the factor of 1.5 is safer and better.