Find the sum of the following series to `n` term: `3xx1^2+5xx2^2+7xx3^2+............`

Explanation

`(n(n+1)(3n^25n+1))/6`


`T_n`=(nth term of `3,5,7,..)`)xx( nth term of `1^2,2^2,3^2....`)


`={3+(n_1)xx2}xx n^2=(2n+1)n^2=2n^3+n^2)`


`S_n= 2(sum_(k=1)^n k^3)+(sum_(k=1)^n k^2)`