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Ponder This

June 2012

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Ponder This Challenge:

Two players starts with the number N and play in turns.
In each turn the player chooses a prime power p^m>1, which divides N and updates N to be N/(p^m).
The player who sets N to be 1 - wins.
What are all the winning moves from the initial state of N=1,506,009,006,001,500,000,000 ?

Update 6/8: We are looking for all the moves the first player can make which, assuming he plays correctly, can guarantee him winning the game.


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We invite visitors to our website to submit an elegant solution. Send your submission to the ponder@il.ibm.com.

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Challenge: 31/05/2012 @ 01:00 PM EST
Solution: 01/07/2012 @ 10:00 AM EST
List Updated: 01/06/2012 @ 10:00 AM EST

People who answered correctly:

Zhendong Wan (05/31/2012 02:38 PM EDT)
Yossi Fendel (05/31/2012 02:47 PM EDT)
Peter de Rivaz (05/31/2012 03:17 PM EDT)
Denys Kopiychenko (05/31/2012 03:25 PM EDT)
Jochen Voss (05/31/2012 03:28 PM EDT)
Sergey Grishaev (05/31/2012 03:31 PM EDT)
William Heller (05/31/2012 03:37 PM EDT)
Hrushikesh Tilak (05/31/2012 03:43 PM EDT)
Tim Nordenfur (05/31/2012 03:48 PM EDT)
Mark Pervovskiy (05/31/2012 04:16 PM EDT)
Florian Fischer (05/31/2012 04:20 PM EDT)
Donald Dodson (05/31/2012 05:19 PM EDT)
Thomas Mack (05/31/2012 05:42 PM EDT)
Dario Serino (05/31/2012 05:51 PM EDT)
Harold Gutch (05/31/2012 06:01 PM EDT)
Deron Stewart (05/31/2012 06:12 PM EDT)
Alex Stangl (05/31/2012 06:23 PM EDT)
Janos Csorba (05/31/2012 06:41 PM EDT)
Deane Stewart (05/31/2012 07:42 PM EDT)
Radu Borza (05/31/2012 08:23 PM EDT)
Jason Lee (05/31/2012 10:01 PM EDT)
Michael Brand (05/31/2012 11:40 PM EDT)
David Dodson (06/01/2012 12:26 AM EDT)
Arthur Vause (06/01/2012 02:47 AM EDT)
Øyvind Grotmol (06/01/2012 03:22 AM EDT)
Robin Ryder (06/01/2012 04:10 AM EDT)
Anlu Wang (06/01/2012 04:14 AM EDT)
Hari MP (06/01/2012 06:50 AM EDT)
Radu-Alexandru Todor (06/01/2012 07:13 AM EDT)
Stéphane Higueret (06/01/2012 08:09 AM EDT)
Armin Krauss (06/01/2012 08:21 AM EDT)
Joseph DeVincentis (06/01/2012 09:27 AM EDT)
Kevin Sham (06/01/2012 09:36 AM EDT)
Avishalom Shalit (06/01/2012 10:12 AM EDT)
Joachim Dörfer (06/01/2012 10:16 AM EDT)
Luke Pebody (06/01/2012 10:40 AM EDT)
Joshua Small (06/01/2012 12:29 PM EDT)
Stefan `Sec` Zehl (06/01/2012 01:59 PM EDT)
Christian Pape (06/01/2012 03:08 PM EDT)
Matej Kollár (06/01/2012 02:07 PM EDT)
Lu Wang (06/01/2012 04:33 PM EDT)
Adrian Orzepowski (06/01/2012 04:53 PM EDT)
Daniel Kneezel (06/01/2012 05:19 PM EDT)
Anders Kaseorg (06/01/2012 06:03 PM EDT)
Ignat Soroko (06/01/2012 06:23 PM EDT)
Yasodhar Patnaik (06/02/2012 12:06 AM EDT)
Leo Broukhis (06/02/2012 04:59 AM EDT)
Clive Tong (06/02/2012 05:09 AM EDT)
Hakan Summakoglu (06/02/2012 05:36 AM EDT)
Karanveer Mohan (06/02/2012 07:39 AM EDT)
Martin Thiim (06/02/2012 08:45 AM EDT)
Serge Gautier (06/02/2012 09:26 AM EDT)
Jonathan Namnath (06/02/2012 10:23 AM EDT)
Peter Gerritson (06/02/2012 05:42 PM EDT)
Siddhartha Kanungo (06/02/2012 07:22 PM EDT)
Naftali Peles (06/02/2012 09:05 PM EDT)
Rogerio Ponce da Silva (06/02/2012 09:44 PM EDT)
Nyles Heise (06/03/2012 12:45 AM EDT)
David Fergemann (06/03/2012 12:00 PM EDT)
Anunay Kulshrestha (06/03/2012 02:40 PM EDT)
David Meiri (06/04/2012 12:21 PM EDT)
Harald Bögeholz (06/04/2012 02:33 PM EDT)
Levon Haykazyan (06/04/2012 03:07 PM EDT)
Walter Schmidt (06/04/2012 05:04 PM EDT)
Chuck Carroll (06/04/2012 06:04 PM EDT)
Eden Hochbaum (06/04/2012 06:46 PM EDT)
Andrew Baine (06/04/2012 07:03 PM EDT)
Erik Bernhardsson (06/04/2012 10:53 PM EDT)
Thomas Fleming (06/04/2012 11:25 PM EDT)
Balakrishnan Varadarajan (06/04/2012 11:41 PM EDT)
Shilei Zang (06/04/2012 11:55 PM EDT)
Simon Xu (06/05/2012 12:49 AM EDT)
Tamir Ganor (06/05/2012 09:09 AM EDT)
John Tromp (06/05/2012 10:37 AM EDT)
Michael Malak (06/05/2012 11:58 AM EDT)
Yue Ru Sun (06/05/2012 12:16 PM EDT)
Liubing Yu (06/05/2012 04:29 PM EDT)
Bryan Wolf (06/05/2012 05:18 PM EDT)
David Friedman (06/05/2012 10:04 PM EDT)
Kenneth Meehan (06/05/2012 11:39 PM EDT)
Frederik Kaster (06/06/2012 05:36 AM EDT)
Markus Boettle (06/06/2012 10:04 AM EDT)
Septimus G. Stevens VII (06/06/2012 10:21 AM EDT)
Danny Scheinerman (06/06/2012 02:46 PM EDT)
Chris St. John (06/06/2012 02:49 PM EDT)
Motty Porat (06/06/2012 05:54 PM EDT)
Krunoslav Kovac (06/06/2012 07:52 PM EDT)
Lewei Weng (06/07/2012 03:37 AM EDT)
Sondre Glimsdal (06/07/2012 08:54 AM EDT)
Lorenzo Gianferrari (06/07/2012 11:09 AM EDT)
Gale Greenlee (06/07/2012 01:27 PM EDT)
Thomas Pensyl (06/07/2012 05:58 PM EDT)
Shmuel Menachem Spiegel (06/07/2012 07:58 PM EDT)
Chris Kittlitz (06/07/2012 09:38 PM EDT)
Ryan Milligan (06/07/2012 10:41 PM EDT)
Xiong Zhang (06/07/2012 11:41 PM EDT)
Amit Bhatia (06/08/2012 06:39 AM EDT)
Hamidreza Bidar (06/08/2012 06:57 AM EDT)
Mihai Stancu (06/08/2012 07:54 AM EDT)
James Aaronson (06/08/2012 11:58 AM EDT)
Colm Bhandal (06/08/2012 12:50 PM EDT)
Rodrigo Coelho (06/08/2012 10:20 PM EDT)
Bernard F. Richardson (06/09/2012 01:52 AM EDT)
Wu Chengyuan (06/09/2012 09:45 AM EDT)
Jonathon Pendergrass (06/09/2012 11:54 AM EDT)
Eric Ivancich (06/09/2012 04:21 PM EDT)
Don Gosiewski (06/09/2012 08:30 PM EDT)
Akshay Nanavati (06/10/2012 02:58 PM EDT)
M. Zecevic (06/11/2012 05:06 AM EDT)
Gil Citro (06/11/2012 10:12 AM EDT)
Djinn Lu (06/11/2012 12:05 PM EDT)
Phil Benamy (06/11/2012 12:39 PM EDT)
Hayk Aleksanyan (06/12/2012 01:38 AM EDT)
Vishaal Kapoor (06/12/2012 03:24 AM EDT)
Tejas Ajit Deshpande (06/12/2012 05:46 AM EDT)
Erik Hostens (06/12/2012 07:14 AM EDT)
Fred Schalekamp (06/12/2012 12:05 PM EDT)
Stephen Morris (06/12/2012 04:37 PM EDT)
Ayaskant Pani (06/13/2012 02:36 AM EDT)
Henri Gonin (06/13/2012 12:44 PM EDT)
Shouky Dan (06/14/2012 05:52 AM EDT)
Duane A. Bailey (06/14/2012 02:34 PM EDT)
Jens Voss (06/15/2012 10:34 AM EDT)
Wolfgang Kais (06/15/2012 11:31 AM EDT)
Arun Ramachandran (06/16/2012 12:23 AM EDT)
Jim Clare (06/16/2012 12:45 PM EDT)
Kun Huang (06/17/2012 03:16 AM EDT)
Guler Amos (06/18/2012 09:45 AM EDT)
Ritobroto Maitra (06/18/2012 03:21 PM EDT)
Daniel Bitin (06/19/2012 09:44 AM EDT)
Dan Arnon (06/19/2012 03:54 PM EDT)
Lawrence Hon (06/20/2012 03:15 PM EDT)
Puvichakravarthy Ramachandran (06/21/2012 03:32 AM EDT)
Ken Crounse (06/21/2012 11:40 AM EDT)
Albert Stadler (06/21/2012 12:47 PM EDT)
Sushanth Kodali (06/21/2012 04:07 PM EDT)
Adrian Kummer (06/21/2012 04:23 PM EDT)
Jake Berkowsky (06/22/2012 01:56 AM EDT)
Franza Cavalcante Jr (06/22/2012 03:31 PM EDT)
Michael D. Moffitt (06/22/2012 03:49 PM EDT)
Tony Harrison (06/24/2012 08:28 AM EDT)
Amit Sinha (06/24/2012 02:28 PM EDT)
Vibhakar Shukla (06/26/2012 01:11 AM EDT)
Dan Dima (06/27/2012 08:52 AM EDT)
Hannes Schenck (06/26/2012 02:57 PM EDT)
Lutz Schaarschmidt (06/26/2012 07:33 PM EDT)
Bradley Sherman (06/27/2012 04:02 AM EDT)
Heiko Selber (06/27/2012 02:30 PM EDT)
Joel Macaluso (06/27/2012 08:29 PM EDT)
Gundars Kokts (06/28/2012 04:51 AM EDT)
Robert Lang (06/28/2012 09:02 AM EDT)
Anees Shaikh (06/28/2012 11:47 AM EDT)
Mutaamba Maasha (06/29/2012 02:01 PM EDT)
Todd Will (06/29/2012 04:49 PM EDT)
Joseph Yoon (06/30/2012 03:55 PM EDT)
Manuel Sanchez-Gestido (06/30/2012 03:58 PM EDT)
Jason Levy (07/01/2012 04:52 AM EDT)


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