# Sequence there !

**Algebra**Level 3

What is the sum of first 25 terms of the sequence where \(n^{th}\) term is defined by the formula

\(a_n = n^2 -2n -1\)

**Details and assumptions**

Sequence starts with \(a_1\) , and it has a value \(a_1 = 1-2-1=-2\)

\(a_2 = 2^2-2\times 2 -1 = -1\)

\(a_3 = 3^2 - 3\times 2 -1 = 2\)

\(a_4 = 4^2-4\times 2 -1 =7\) . . . .