1/1(4) + 1/4(7) + 1/7(10)+....+ 1/(3n-2)(3n+1)
and the sigma notation is pretty obvious
The Attempt at a Solution
I can see an obvious pattern its n(n+3) but n cannot be 2,3,5,6 etc.. and the second digit in the first term becomes the first digit in the next term. I think its fairly simply but I've just been staring at it blankly and i think ive passed that point where im doing any useful thinking so an answer or even a hint would be great.