Bounded Sequence Calculator

Study limits, bounds, and oscillation with sequence controls. Compare families, inspect terms, and spot divergence. Clear outputs help verify upper and lower bounds accurately.

Calculator Inputs
Choose a family or supply your own terms.
Graph and table begin at this term number.
Use more terms to inspect long-run behavior.
Separate values with commas, spaces, or semicolons.
Example data table

This example uses the shifted reciprocal sequence aₙ = 2 + 5 / (n + 1).

n Formula result Interpretation
14.500000Largest term in this family for n ≥ 1
23.666667Still above the limit 2
33.250000Sequence decreases
43.000000Approaches the horizontal limit
52.833333Bounded between 2 and 4.5
62.714286Confirms bounded, convergent behavior

Formula used

1) Arithmetic sequence

aₙ = a₁ + (n - 1)d. It is bounded only when the common difference is zero, or one-sided bounded when the difference has a fixed sign.

2) Geometric sequence

aₙ = a₁ · r⁽ⁿ⁻¹⁾. It is bounded for |r| ≤ 1 when the sequence does not grow in magnitude. It becomes unbounded when magnitude increases without limit.

3) Shifted reciprocal sequence

aₙ = c + a / (n + b). For b > -1, the denominator stays positive for all n ≥ 1, so the sequence stays between its first term and the limit c.

4) Alternating reciprocal sequence

aₙ = c + a · (-1)ⁿ / (n + b). The oscillation shrinks in magnitude and the sequence converges to c, while remaining inside a fixed interval.

5) Linear fractional sequence

aₙ = (p·n + q) / (r·n + s). When the denominator never becomes zero at a positive integer, the sequence is bounded and converges to p / r if r ≠ 0.

6) Sample extrema

The calculator also reports sampled minimum, sampled maximum, average value, sign changes, and monotonicity across your chosen term window.

How to use this calculator

  1. Choose a sequence family or enter a manual list of terms.
  2. Set the sample start index and the number of terms to generate.
  3. Enter the parameters for the selected family, such as ratio, difference, or coefficients.
  4. Optionally add a claimed lower bound, upper bound, or both to test your guess.
  5. Click Submit to show the result above the form, including a Plotly graph and term table.
  6. Use the CSV and PDF buttons to export the analysis for notes, classes, or reports.

FAQs

1) What does bounded mean for a sequence?

A sequence is bounded if every term stays inside some fixed interval. Bounded above means terms never exceed one constant. Bounded below means terms never fall below one constant.

2) Does a finite manual list prove an infinite sequence is bounded?

No. A finite list is always bounded because it has a smallest and largest value. That does not prove future unseen terms remain inside the same interval.

3) Can a sequence be bounded and still fail to converge?

Yes. The classic example is an alternating pattern such as (-1)ⁿ. Its terms stay within fixed limits, but they do not settle to one value.

4) Why does the calculator show sampled bounds and theoretical bounds?

Sampled bounds come from the displayed term window. Theoretical bounds use known formulas for built-in families. Both are useful because samples show behavior visually while theory explains the full sequence.

5) What is the difference between supremum and maximum here?

A maximum is an actual largest term achieved by the sequence. A supremum is the least upper bound, which may exist even when no term reaches it exactly.

6) Why do reciprocal modes require shift b greater than -1?

That condition keeps n + b positive for all positive integers n. It avoids denominator problems and makes the bound interpretation cleaner and mathematically reliable.

7) What does sign-change counting tell me?

It measures how often nonzero terms switch between positive and negative values in the displayed sample. This helps identify oscillation, alternating behavior, or movement across the horizontal axis.

8) When should I increase the number of sample terms?

Increase the sample size when a sequence changes slowly, oscillates, or approaches a limit gradually. A longer window gives a better visual sense of long-run behavior.

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Important Note: All the Calculators listed in this site are for educational purpose only and we do not guarentee the accuracy of results. Please do consult with other sources as well.