- #1

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## Homework Statement

Find the sum of the products of every pair of the first 'n' natural numbers.

## Homework Equations

sigma n^2 = n(n+1)(2n+1)/6

## The Attempt at a Solution

S=1.2 + 1.3 + 1.4 ...+ 2.3 + 2.4 ...n-1(n)

i can't figure out how to proceed ..