sum(1/((5*n+1)*(5*n+2)*(5*n+3)*(5*n+4)*(5*n+5)), n = 0 .. infinity)

Uh oh! Wolfram|Alpha doesn't run without JavaScript.

Please enable JavaScript. If you don't know how, you can find instructionshere.Once you've done that, refresh this page to start using Wolfram|Alpha.