f on I is continuous at a point c ∈ I iff for every sequence {cₙ} in I , cₙ→c , we have, f(cₙ)→f(c) 

A function f defined on an interval I is continuous at a point c ∈ I iff for every sequence {cₙ} in I , cₙ→c , we have , f(cₙ)→f(c)