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theorem proved term proof

fib_recurrence_at_6

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formal statement (Lean)

  43theorem fib_recurrence_at_6 : fib 6 = fib 5 + fib 4 := by

proof body

Term-mode proof.

  44  rw [fib_6_eq, fib_5_eq, fib_4_eq]
  45
  46/-- Key identity: 8 - 3 = 5, or F₆ - F₄ = F₅ -/

depends on (9)

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