How it works
Find terms, partial sums, and a preview for arithmetic, geometric, or Fibonacci sequences. Inputs are calculated locally in the browser, and valid values are retained in the page URL for bookmarking.
Input query strings and outputs
Use an input name in this page’s URL as ?name=value, and join additional inputs with &. Portable shared links may instead use the compact ?ac= state parameter.
Input query strings
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?sequenceType=Sequence typeChoice · Required · Default: arithmetic · Accepted values: arithmetic, geometric, fibonacci
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?firstTerm=First termNumber · Required · Default: 1
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?commonValue=Common difference or ratioNumber · Required · Default: 2
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?termNumber=Term number (n)Number · Required · Default: 10
Outputs
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nthTermn-th termText · Primary output
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sumSum through nText
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sequencePreviewFirst termsText
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sequenceTypeLabelSequence typeText
Formula notes
Arithmetic: aₙ=a₁+(n−1)d; geometric: aₙ=a₁rⁿ⁻¹; Fibonacci: Fₙ=Fₙ₋₁+Fₙ₋₂.
Input guidance
Use consistent units for every length or measurement in the same calculation. Results are educational mathematical estimates and should be checked before high-stakes use.