How to use formula in webadi (Sample of using formula's in WebADI layout)

Sample of using formula's in WebADI layout:

There are requirements when we want to create a sequence in webadi layout based without using actual sequence, as sequence creation at row level is difficult, and generally done using pre-import step (could not do it because of issue i faced), there is a workaround.

While defining the layout, just provide below text while selecting column type as formula
anything in [] will represent the reference columns, an example is below

=IF([INVOICE_NUMBER]<>"",ROW()-10,"")