Recurrence Relation Calculator

Solve linear recurrence relations, find characteristic roots, and closed-form solutions.

Recurrence Type

a_n = 1a_{n-1} + 1a_{n-2}

Sequence

0, 1, 1, 2, 3, 5, 8, 13, 21, 34, ...

Closed Form

a_n = 0.4472×(1.6180)^n + -0.4472×(-0.6180)^n

Characteristic Roots

r₁ = 1.618034

r₂ = -0.618034

Discriminant: 5.0000

Ratio Limit

lim(aₙ₊₁/aₙ) ≈ 1.6180257511

Full Sequence

a_0=0a_1=1a_2=1a_3=2a_4=3a_5=5a_6=8a_7=13a_8=21a_9=34a_10=55a_11=89a_12=144a_13=233a_14=377

Recurrence Relations

Solving Method

  1. Find characteristic equation: r² - c₁r - c₂ = 0
  2. Solve for roots r₁, r₂
  3. General solution: aₙ = Ar₁ⁿ + Br₂ⁿ
  4. Use initial conditions to find A, B

Special Cases

  • Repeated roots: aₙ = (A + Bn)rⁿ
  • Complex roots: involves trig functions
  • Fibonacci: φⁿ/√5 approximation