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Microsoft Azure Notebooks - Live code - F#, R, and Python

I was exploring Jupyter notebooks , that combines live code, markdown and data, through Microsoft's implementation, known as MS Azure Notebooks , putting together a small library of R and F# notebooks . As Microsoft's FAQ for the service describes it as : ...a multi-lingual REPL on steroids. This is a free service that provides Jupyter notebooks along with supporting packages for R, Python and F# as a service. This means you can just login and get going since no installation/setup is necessary. Typical usage includes schools/instruction, giving webinars, learning languages, sharing ideas, etc. Feel free to clone and comment... In R Azure Workbook for R - Memoisation and Vectorization Charting Correlation Matrices in R In F# Charnownes Constant in FSharp.ipynb Project Euler - Problems 18 and 67 - FSharp using Dynamic Programming

Project Euler - Problem #25

Description

The Fibonacci sequence is defined by the recurrence relation:

    F_(n) = F_(n−1) + F_(n−2), where F_(1) = 1 and F_(2) = 1.

Hence the first 12 terms will be:

    F_(1) = 1
    F_(2) = 1
    F_(3) = 2
    F_(4) = 3
    F_(5) = 5
    F_(6) = 8
    F_(7) = 13
    F_(8) = 21
    F_(9) = 34
    F_(10) = 55
    F_(11) = 89
    F_(12) = 144

The 12th term, F_(12), is the first term to contain three digits.
What is the first term in the Fibonacci sequence to contain 1000 digits?
    Solution

    open System.Numerics

    //tail-recursion to return Fibonacci based on length of a number's string
    let rec fibsRecTailBigIntSingle (x:BigInteger) (y:BigInteger) acc max =
        let lenY = (y.ToString()).Length
        if lenY >= max then
            acc + 1
        else
            let next = x + y
            let item = acc + 1
            fibsRecTailBigIntSingle y next item max

    let Prob25_1 = fibsRecTailBigIntSingle 1I 1I 1 1000

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