Is there a way to programmatically insert formulas into a csv file using vb.net?

1,2,3,=SUM(A1:C1)

Surprised me when I tried it, but Excel will keep the formula.

You can even export formulas into a CSV by first displaying them on screen. (Ctrl-`)

While I stand by that my original answer is technically correct, I have been getting a lot of downvotes on this. Apparently popular spreadsheet software such as Microsoft Excel, Open Office, Libre Office Calc will calculate formulas that are entered into a CSV file. However, I would still not recommend relying in this capability.

Original answer:
The CSV format does not support formulas. It is a plain text only format.