Evaluate 1 x 2^2 + 3 x 4^2 + 5 x 6^2 +... to n terms

I have been using (2n-1)(2n^2) as my nth term. After finding my sum to n terms, i have been substituting a value in, continuously it is not coming out as intended. Possibly my nth term is incorrect. I have been using the rth term expressed as a polynomial in r method.

Thanks.