a puzzle sequence

Graeme McRae g_m at mcraefamily.com
Fri Jul 29 22:52:31 CEST 2005

Has anyone had any luck with this one?  I posted this question on a math 
board I frequent (nrich.maths.org) but so far the only comments have been 
that the numbers alternate between two-digit and three-digit, and that they 
are a pair of primes followed by a pair of non-primes, and continuing to 
alternate in that fashion.  I googled for "87   711   43   269   65   555 
39   421   17" and saw someone asked the question back in February, on the 
FreeMathHelp.com message board, as follows:

Full Member
Joined: 28 Dec 2004
Posts: 109
Location: New York City
 Posted: Wed Feb 23, 2005 11:47 am    Post subject: Pattern
87, 711, 43, 269, 65, 555, 39, 421, 17,.......
What are the next 5 numbers?
Thank you for your help,

Senior Member
Joined: 17 Feb 2004
Posts: 844
Location: Ottawa, Ontario
 Posted: Wed Feb 23, 2005 11:37 pm    Post subject:
s'that supposed to be mathematical, or alpha related,
or just a plain old puzzle?
I'm just an imagination of your figment!

But then there was no follow-up with answers to Denis' questions or an 
actual answer.  I googled for "ritanyc" and found an email address, but who 
knows if there are many ritas in nyc?  I bet there are.  In any case, I sent 
an email to that address asking if she ever got an answer to this question. 
I'll let you know if anything turns up.  In the mean time, has anyone else 
made any progress?


----- Original Message ----- 
From: "N. J. A. Sloane" <njas at research.att.com>
To: <seqfan at ext.jussieu.fr>
Sent: Tuesday, July 26, 2005 5:49 AM
Subject: a puzzle sequence

> SeqFans,  this just came in. Can anyone solve it?
> I don't know the answer.  NJAS
>> need help with a math thing
>> 87   711   43   269   65   555   39   421   17   ___    ___    ___
>> What are three numbers?  What is the pattern?  What do they have in 
>> common?
>> If you could help it would be great!!

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