We need to stop pretending that Excel's built-in functions are the end of the story. The user who posted this problem knows exactly what they need: a single-cell formula that computes the harmonic-like series ∑ 1/(x·n) for n=1 to n=x, repeated hundreds of times with different x values. They've done the research, tried SERIESSUM and SEQUENCE, and hit a wall. That wall isn't a limitation of their math skills, it's a limitation of the tool's design when faced with anything beyond power series or linear sequences. The honest take here is that Excel's formula engine, for all its power, still treats custom summation as an afterthought. SERIESSUM is rigidly tied to power series. SEQUENCE generates arrays but offers no built-in way to apply an arbitrary function to each element before summing. The user's instinct to combine them is correct, but the implementation falls short because Excel's array context doesn't naturally support a parameter like "1/n" as a coefficient inside SERIESSUM's coefficient argument. That's not a user error, it's a product gap.
The practical solution isn't more formula gymnastics. It's a shift in thinking. What this user actually needs is a tool that treats "create a series from a rule and sum it" as a first-class operation, not a workaround. In modern AI-native spreadsheets, you'd write something like `=SUM(SEQUENCE(x, 1, 1, 1) |> MAP(n -> 1/(x*n)))`, or an even more direct expression that reads as the math itself. The formula should match the problem, not the other way around. The fact that this user has to hunt through documentation, weigh the quirks of SERIESSUM's coefficient ordering, and then still come up empty tells us that the spreadsheet industry has been coasting on legacy function sets for too long. Users shouldn't need to "finagle" calculus to do repetitive arithmetic.
What this means for you is straightforward: if you're spending time adapting your data to fit a formula's constraints, you're using the wrong tool. The future of spreadsheet work isn't about memorizing arcane function signatures, it's about describing what you want in plain logic and letting the system handle the execution. That user's problem is solvable today with a few lines of Python in an AI-enabled environment, or with a custom LAMBDA in Excel if you're willing to write it yourself. But the better answer is a spreadsheet that understands series notation natively. Until then, the most productive thing you can do is recognize when a tool is asking you to work around its limits, and start exploring alternatives that don't.