Fibonacci Calculator
One entry per line - the Nth term, the first N terms, or an index range
Mode:
Sequence Type:
Max results:
Separator:
Calculation Result
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| No. | No. | Value | Digits |
|---|
Introduction to the tool and how to use it
The Fibonacci calculator (rabbit sequence) covers three common needs in one input box: one entry per line, and many lines may be pasted at once.
Internally it uses fast doubling: F(2k) = F(k) × (2F(k+1) − F(k)) and F(2k+1) = F(k)² + F(k+1)², requiring only O(log n) big-integer multiplications. As a result, a 21-digit value such as F(100) = 354224848179261915075, and even the 209-digit result F(1000), come out complete and exact, with none of the precision loss a floating-point implementation suffers. The index cap is 10000 (about 2090 digits), and a single run outputs at most 500 terms.
Internally it uses fast doubling: F(2k) = F(k) × (2F(k+1) − F(k)) and F(2k+1) = F(k)² + F(k+1)², requiring only O(log n) big-integer multiplications. As a result, a 21-digit value such as F(100) = 354224848179261915075, and even the 209-digit result F(1000), come out complete and exact, with none of the precision loss a floating-point implementation suffers. The index cap is 10000 (about 2090 digits), and a single run outputs at most 500 terms.
How to use
- Choose a mode:
· Nth term: one index per line, such as100(counting starts from F(0)=0);
· First N terms: a term count per line, such as20, outputting F(0) ~ F(N-1);
· Index range: one range per line, such as10,20; reversed start and end are swapped automatically. - Switch the sequence type if needed: Fibonacci F(n) or Lucas L(n) (L(0)=2, L(1)=1); both share the same input.
- Click calculate; the result table lists each term's index, value, and digit count, with one-click copy and CSV export.
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