InterviewSolution
`N(2N^(2) + 9n+1))/( 6) ``(2n^(2) + 9n+1)/( 6)``(2n^(2) + 9n+1)/( 12)``(2n^(2) + 9n+1)/( 24)`
Your experience on this site will be improved by allowing cookies. Read Cookie Policy