[Email Scraper Plugin – URL Generator] 2 distinct PAGENUM

Hi everyone,

I’m using the URL Generator in the Email Scraper to scrape a directory. The URLs look like this

Code:
https://domaine.fr/page?keyword&from=1&to=20
https://domaine.fr/page?keyword&from=21&to=40
https://domaine.fr/page?keyword&from=41&to=60
...
https://domaine.fr/page?keyword&from=1781&to=1800

So I tried 
https://domaine.fr/page?keyword&from=1&to={pagenum}
but the website crashes when the pagenum is too high.

I want to do something like
https://domaine.fr/page?keyword&from={pagenum-20+1}&to={pagenum}

I tried with
https://domaine.fr/page?keyword&from=&to={pagenum}
with  1, 21, 41, 61, etc… as , (from an Excel) but I have thousand of useless URLs…

Can someone help me?

Thanks!