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Conference rusure::math

Title:Mathematics at DEC
Moderator:RUSURE::EDP
Created:Mon Feb 03 1986
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:2083
Total number of notes:14613

1353.0. "Osman's conjecture (palindromic sequences in square roots as continued fractions)" by HANNAH::OSMAN (see HANNAH::IGLOO$:[OSMAN]ERIC.VT240) Tue Dec 11 1990 14:38

As shown in many number theory books, given any positive integer whose square
root is irrational, the root can be represented as a repeating continued
fraction.

For example:

sqrt(983) = 31 2 1 5 31 5 1 2 62 2 1 5 31 5 1 2 62 2 1 5 31 5 1 2 62 ...

In this case, the "2 1 5 31 5 1 2 62" repeats forever.

In case you're not familiar with continued fractions, this means

sqrt(983) = 31+1/(2+1/(1+1/(5+1/(31+1/(5+1/(1+1/(2+1/...

My conjecture:

	The pattern of numbers not counting the last number of the pattern
	is always a palindrome.

In our example, it's easy to see we have a palindrome:

	2 1 5 31 5 1 2

Am I the first to recognize this fact ?  Is it interesting or just ho hum ?
I'm not sure how to go about proving it yet.

/Eric
T.RTitleUserPersonal
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1353.1intersting..SMAUG::ABBASITue Dec 11 1990 18:225
    Have you tested OSMAN conjecture on a large number of such positive
    integers whose square root is irrational? may be by writing a program?
    
    your conjecture is intersting if it comes to be true..
    /nasser
1353.2well spottedHERON::BUCHANANcombinatorial bomb squadWed Dec 12 1990 07:545
	It's true.   I have the proof somewhere.   Galois did it when he was
a brat.

Regards,
Andrew.
1353.3But then,VMSDEV::HALLYBThe Smart Money was on GoliathWed Dec 12 1990 11:511
    Galois DIED when he was still a brat!
1353.4poor chapHERON::BUCHANANcombinatorial bomb squadWed Dec 12 1990 12:2212
>    Galois DIED when he was still a brat!

	1829 [the year the first railway opened, from Stockton to Darlington in 
England] saw the publication of Galois' first paper, on continued fractions.   
He was aged 18.   He died 31 May 1832, of peritonitis following an absurd 
duel the previous day.   Fortunately for mathematics, he had taken the
precaution the evening before the duel to write a letter to his friend Auguste
Chevalier outlining the connection between groups and polynomial equations,
including his fundamental solubility theorem, and many other ideas.

Regards,
Andrew.
1353.5Leads to Solution of Pell's EquationTROA09::RITCHEFrom the desk of Allen Ritche...Wed Dec 12 1990 18:5718