Tribonacci Number Calculator

About this calculator

The Tribonacci sequence generalizes the Fibonacci idea one step further: instead of adding the previous two terms, each term is the sum of the previous three (T₀=0, T₁=1, T₂=1, and Tₙ = Tₙ₋₁ + Tₙ₋₂ + Tₙ₋₃ from there on). As n grows, the ratio of consecutive terms converges to the tribonacci constant (≈1.839286755), the real root of x³ = x² + x + 1, playing a role for this sequence similar to what the golden ratio plays for Fibonacci numbers.

Computer science students meet it in recursion and dynamic-programming exercises (it's a classic LeetCode-style problem), while number theorists and recreational mathematicians use it to explore generalized Fibonacci-like sequences (tetranacci, pentanacci, and beyond follow the same pattern with more terms). Enter n to get Tₙ instantly without hand-computing the recursion.