Fibonacci Sequence Generator
Generate any number of Fibonacci terms — including very large ones, using BigInt.
F(0) – F(14) · 15 terms
About the Fibonacci sequence
The Fibonacci sequence starts with 0 and 1; each subsequent term is the sum of the two before it: 0, 1, 1, 2, 3, 5, 8, 13, 21 … The ratio of consecutive terms approaches the golden ratio φ ≈ 1.618. Standard JavaScript numbers lose precision above F(78) ≈ 8.9×10¹⁶, so this tool uses BigInt arithmetic and can generate F(200) — a 42-digit number — exactly. Fibonacci numbers appear in nature (flower petals, spiral shells), algorithm design (search, heaps), and as the classic introduction to recursive and dynamic programming. For other number-theory tools, see Prime Number Checker and GCD & LCM Calculator.
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