Project Euler #2: Even Fibonacci numbers

  • + 2 comments

    Your post was the most helpful.

    I'm just wondering why no one has posted an ACTUAL answer to this problem in over 4 years.

    Which means

    is the solution to it. Now the trick is to find a fast way to compute what n might actually be .

    • + 0 comments

      Fibonacci_index

      It's not perfect. When k = 12, n = 7. However, the n-th term for F is 13. We can check agaisnt this quickly with the same formula going forwards and backwards ONCE. instead of over a loop like everyone has been doing.

      I should mention the relationship I gues. F_0 = 0, E = F_{3n}

    • + 0 comments

      I should mention, all this is useless past a certain point on a computer since percision is slowly lost. However, NASA has a great article on how accurate pi needs to be.