Find the sum of first `n` terms of the following series:`5+11+19+29+41+..................`

Explanation

`5+11+19+29+41 ldots=(1+2^{2})+(2+3^{2})+(3+4^{2}) + (4+5^{2})`


`t n =n+(n+1^{2})`


`=n+n^{2}+2 n+1 `


`=n^{2}+3 n+1 `


`S n =sum(n^{2}+3 n+1) `


`=sum n^{2}+3 sum n+sum 1`


`=n(n+1)(2 n+1) / 6+3 n(n+1) / 2+n `


`=n(2 n^{2}+2 n+n+1+9 n+9+6) / 6 `


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