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 Post subject: great number sequencePosted: Mon Jul 11, 2005 5:54 pm

Joined: Thu Dec 09, 1999 11:07 am
Location: Los Angeles, CA
This is my favorite self-generating sequence:

1
11
21
1211
111221
312211
13112221
1113213211
31131211131221
13211311123113112211

[hint: just read each line out loud]

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 Post subject: Posted: Mon Jul 11, 2005 7:15 pm

Joined: Fri Feb 18, 2000 8:50 am
Location: chicago, IL area U.S.A
One of my favorites as well. It seems to pop up on rec.puzzles frequently as well.

-d

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 Post subject: Posted: Mon Jul 11, 2005 7:56 pm

Joined: Thu Jan 06, 2005 8:53 pm
Location: Los Angeles
Hey, tie in with another thread ...
Level80 on notpron uses that exact sequence as a fake username/password clue.

TBTTFox

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 Post subject: Posted: Mon Jul 11, 2005 10:22 pm

Joined: Thu Dec 09, 1999 11:07 am
Location: Los Angeles, CA
If I remember its called a "Morse-Thule sequence"

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 Post subject: Posted: Tue Jul 12, 2005 5:21 am

Joined: Wed Oct 31, 2001 4:19 am
Location: Manchester, UK
If I remember its called a "Morse-Thule sequence"

I've seen this called "Conway's Recursive Sequence" or similar, but not sure that he was the first to think of it. There are a number of variations on the idea.

You might be thinking of the Thue-Morse Sequence. There may well be a connection, though: each term of the CRS contains only 1,2,3 (so you don't get more than 3 consecutive digits that are the same), whereas the Thue-Morse sequence contains only 0 and 1, with never more than 2 consecutive digits (or even strings of digits) the same.

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 Post subject: Posted: Wed Jul 13, 2005 1:04 pm

Joined: Thu Jan 24, 2002 1:10 am
That's a new one for me. It's always fun looking these things up.

I found it called "Audioactive Sequence" and "Look and Say Sequence" in different places. Here's a link to MathWorld:

http://mathworld.wolfram.com/LookandSaySequence.html

Sandy

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