Why is the Eucharist not important.

who said that in fact it is really important

Explanation:

its the central part of all Christianity.According to the Compendium of the Catechism of the Catholic Church "The Eucharist is the very sacrifice of the Body and Blood of the Lord Jesus which he instituted to perpetuate the sacrifice of the cross throughout the ages until his return in glory. ... this sacrifice is truly propitiatory."

reference from Bible (Gospel of Saint John 6:25-59)

or (Catechism of the Catholic church 1322-1419) I wish you read those .

to answer your question:

f(x)= a^x.  if x=0, f(x)=1  if x=1, f(x)=a  if x=1, f(x)=a^a