Checking a proof by induction

We want to prove by induction that, for every integer n >= 1, the sum of squares 1^2 + 2^2 + ... + n^2 = n(n+1)(2n+1)/6. Write the base case (rank n=1) and explain, without necessarily redoing the whole inductive-step calculation, which expression should appear in the inductive step just before using the induction hypothesis.