```Date: Jan 27, 1999 4:46 PM
Author: Sarah Seastone
Subject: Re: coins problem

See if this helps:12 coins problem  - Frans Faasehttp://home.wxs.nl/~faase009/Ha12coins.htmlAt 3:02 PM -0500 1/27/99, Helena Verrill wrote:>a little while ago, someone asked the following:>>if you have 12 coins, one of which is either>heavier or lighter than the others, the others all>being the same weight, how can you determine which>one it it, and whether it's heavier or lighter, in>three weighings.>>Well, I did't think about this problem until last>weekend when I heard it for a second time.>Anyway, it's not too hard to solve, but how about>what is the minumum number of weighings that you>need to determine which is the odd one, and whether>it's heavy or light, from n coins?>Eg, you can do 3 coins in 2 weighings,>12 coins in 3, 38 coins in 4 weighings ->I'd rather ask for what is the sequence a_n>so that a_n is the maximum number of coins such>that the odd one can be found (and said to be heavier>or lighter).  I'd guess this starts 3,12,38...>but I can't find this sequence in Sloanes integer>sequences, so presumably that means 38 is not the>max you can do in 4 weighings... Anyone else tried?>>HelenaSarah SeastoneEditor, Archivist, Web Page DesignerThe Math Forumhttp://forum.swarthmore.edu/
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