(October 21, 2016 at 10:19 pm)Aractus Wrote:(October 21, 2016 at 10:07 pm)Tiberius Wrote: 1 + 2 + 3 + ... = -1/12 is correct as a Ramanujam summation:
https://en.m.wikipedia.org/wiki/1_%2B_2_...%2B_4_%2B_⋯
It's not correct because it's not a sum it's a series. You can calculate the value of an infinite convergent series, but not a divergent one. The term as written is a bastardisation of the equals sign in which it means "is associated with" and not "is equal to". Anyway that's besides the point because for this problem you do not need to use some shifty value for an infinite divergent series, you just need to know the series and how to calculate the value to the nth term of the series.
You can calculate the sum of a divergent series using Ramanujam summation. That's what it was invented for. Its not a true sum of the series of course, but it works and is used to study actual divergent series'.