Let's make it clear: 1+2+3+... is a divergent series, admitting infinity as a limit. However, there are multiple ways of defining a "summation" of the series.

Let's make it clear: 1+2+3+... is a divergent series, admitting infinity as a limit. However, there are multiple ways of defining a "summation" of the series. Ramanujan's technique confirms the analytic continuation of Riemann's zeta function: zeta(-1) -> -1/12 So the equal sign actually means "there exists a summation technique leading to that result". That's why the original formula reads: 1 + 2 + 3 + 4 ... = -1/12 (R) The (R) indicates Ramanujan's specific summation.