I'm encountering numerical accuracy issues when computing the infinite series: NSum[Sin[Sqrt[k]]/k, {k, 1, ∞}, WorkingPrecision -> 20] Despite setting WorkingPrecision -> 20, Mathematica seems to produce inconsistent or inaccurate results for this slowly convergent series. I've identified several computational errors in the evaluation. Has anyone experienced similar issues with NSum for oscillatory series like this? Are there better approaches or alternative methods to reliably compute such...
