Did the Jansenists deny the gratuity of grace?

Did the Jansenists deny the gratuity of grace? That is, did they think praying more or doing more works of supererogation could always coerce God into granting them more grace, not that God grants or withholds grace as he pleases? >Ephesians 2:8-10 For by grace you are saved through faith, and that **not of yourselves**, for **it is the gift of God**; not of works, that no man may glory. For we are his workmanship, created in Christ Jesus in good works, which God hath prepared that we should walk in them.