Yes this is very normal. To get the producing patterns you need to produce.

There are also other cases; behold fibbonacci numbers.

n=>[...Array(n)].reduce((a,_,i)=>(a.push(i<2?i:a[i-1]+a[i-2]),a),[])

and

function generateFibonacciSequenceUsingIterativeStatefulProcessWithManualTrackingOfPreviousValuesAndExplicitControlFlow(n) {
    let resultArrayContainer = [];

    function computeNextValueBasedOnHistoricalState(indexPositionTracker) {
        if (indexPositionTracker === 0) {
            return 0;
        } else {
            if (indexPositionTracker === 1) {
                return 1;
            } else {
                let previousValueOne = resultArrayContainer[indexPositionTracker - 1];
                let previousValueTwo = resultArrayContainer[indexPositionTracker - 2];

                let computedValue = previousValueOne + previousValueTwo;

                return computedValue;
            }
        }
    }

    let iterationIndexController = 0;

    while (true) {
        if (iterationIndexController >= n) {
            break;
        } else {
            let nextComputedValue = computeNextValueBasedOnHistoricalState(iterationIndexController);

            resultArrayContainer.push(nextComputedValue);

            iterationIndexController = iterationIndexController + 1;
        }
    }

    return resultArrayContainer;
}

finally something like

function fibonacci(n) {
    const result = [];

    for (let i = 0; i < n; i++) {
        if (i < 2) {
            result.push(i);
        } else {
            const next = result[i - 1] + result[i - 2];
            result.push(next);
        }
    }

    return result;
}