To prove P(1), we must show that when 1 is substituted
into the equation in place of n, the left-hand side equals
the right-hand side. But when 1 is substituted for n, the
left-hand side is the sum of all the even integers from 2
to 2· 1, which is just 2, and the right-hand side is 12 + 1,
which also equals 2. Thus P(1) is true.