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Re: composites

  • Subject: [mg3401] Re: [mg3362] composites
  • From: brucec (Bruce Carpenter)
  • Date: 4 Mar 1996 06:51:50 -0600
  • Approved: usenet@wri.com
  • Distribution: local
  • Newsgroups: wri.mathgroup
  • Organization: Wolfram Research, Inc.
  • Sender: daemon at wri.com

>In the sequence of counting numbers, what is the first stretch of
>one hundred composite numbers?
>
>Will Self

Hi Will,

The following code searches for the first gap between primes which is
greater than or equal to 100:

In[45]:=

FixedPoint[(#+1)&, 2,
     SameTest -> (Prime[#2] - Prime[#1] >= 101&)]

Out[45]=

31546

This means that there are at least 100 composites between the 31545th and
the 31546th prime number.

In[46]:=

Prime[31545]

Out[46]=

370261

In[47]:=

Prime[31546]

Out[47]=

370373

The stretch you are looking for actually consists of 111 composites, from
370262 to 370372.

Best Regards,

Bruce Carpenter

-----------------------
Bruce Carpenter
Courseware Coordinator         phone: (217) 398-0700
Wolfram Research, Inc.           fax: (217) 398-0747
100 Trade Centre Drive         email: brucec at wolfram.com
Champaign, IL  61820             web:  http://www.wolfram.com




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