Sum of reciprocals ?

Mathcads symbolics seems not to be able to cope with this sum and thats no surprise.

You can rewrite your sum using the Catalan identity, but to no avail

For special calculations in number theory you should not use Mathcad but rather a specialized CAS.
A widespread one is PARI/GP which can be downloaded here: http://pari.math.u-bordeaux.fr

P.S.: I haven't tried if PARI can come up with the desired result 1, though.

EDIT: I tried using the online browser version of PARI/GP (https://pari.math.u-bordeaux.fr/gp.html), but the result rather looks like a numeric one, not a symbolic 1

So PARI sure can handle very large numbers and has handy and valuable function when dealing with number theory, but it can't be used to symbolically prove that the infinite sum is exactly 1.

P.P.S.: I noticed that the numerator and denominator of the (fully reduced) fractions in my examples always differ by exactly 1.
Is this a coincidence? 🤔