What is the sum of the first 15 terms of the following series? 2^2, 3^2, 4^2, 5^2, ...

The sum of the squares 2^2 to 15^2 is 1239.

Use the formula 1^2 + 2^2 + ... + n^2 = n(n+1)(2n+1)/6.

For n = 15 the total is 15 x 16 x 31 / 6 = 1240.

Remove 1^2 to start the series from 2^2.

1240 - 1 = 1239.