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Rosetta: Primorial numbers

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> Primorial numbers are those formed by multiplying successive
> prime numbers.
> 
> The primorial number series is: 
> 
>   primorial(0) =         1       (by definition)
>   primorial(1) =         2       (2)
>   primorial(2) =         6       (2*3)
>   primorial(3) =       30       (2*3*5)
>   primorial(4) =     210       (2*3*5*7)
>   primorial(5) =   2310       (2*3*5*7*11)
>   primorial(6) = 30030       (2*3*5*7*11*13)
> 
> Show the first ten primorial numbers (0 -- 9, inclusive).
> 
> Show the length of primorial numbers whose index is:
> 10 100 1,000 10,000 and  100,000.
> 
> Show the length of the one millionth primorial number (optional). 
> 
> Use exact integers, not approximations.

(use streams streams-math)
(use numbers)
(use srfi-42)

(define primorials (stream-scan * 1 prime-numbers-stream))

(define (primorial i)
  (stream-fold * 1 (stream-take i prime-numbers-stream)))

(stream->list 10 primorials)

(do-ec
  (:range i 1 6)
  (:let j (expt 10 i))
  (print "length of primorial " j ": "
    (string-length (number->string (primorial j)))))


(1 2 6 30 210 2310 30030 510510 9699690 223092870)

length of primorial 10: 10
length of primorial 100: 220
length of primorial 1000: 3393
length of primorial 10000: 45337
length of primorial 100000: 563921

In Forth?

-- 
Goyim were born only to serve us. Without that, they have no place in the
world---only to serve the People of Israel....  They will work, they will plow,
they will reap. We will sit like an effendi and eat. --- Rabbi Ovadia Yosef
https://web.archive.org/web/20101020044210/http://www.jpost.com/JewishWorld/JewishNews/Article.aspx?id=191782
http://archive.org/download/DavidDuke_videos/TopRabbiExposesJewishRacism-cybsdwjezqi.ogv

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Rosetta: Primorial numbers "Robert L." <No_spamming@noWhere_7073.org> - 2017-05-13 04:29 +0000

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