[seqfan] Re: confused about toothpick sequence A139250!

Rob Pratt Rob.Pratt at sas.com
Mon Apr 13 23:33:01 CEST 2009

A guess:

Define an endpoint of a toothpick to be "exposed" if it does not touch another toothpick.  Then a(n) counts the number of exposed endpoints of toothpicks (of unit length) after n steps, where in each step a new toothpick is placed perpendicularly adjacent to an exposed endpoint.

-----Original Message-----
From: seqfan-bounces at list.seqfan.eu [mailto:seqfan-bounces at list.seqfan.eu] On Behalf Of N. J. A. Sloane
Sent: Monday, April 13, 2009 5:23 PM
To: seqfan at seqfan.eu
Subject: [seqfan] confused about toothpick sequence A139250!

Could someone explain sequence A139250 ?



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