Find the sum of the firstnterms of the series:

(i) 1.3.5 + 3.5.7 + 5.7.9 + ... + (2n- 1)(2n +1)(2n+3)

(ii) 1/(1.3.5) + 1/(3.5.7) + 1/(5.7.9) + ... + 1/[(2n- 1)(2n +1)(2n+3)]

I have tried many methods, but with no avail... how can i solve this while displaying working and explanations??