cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

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A055213 Number of n-piece positions at checkers, for n=1 ... 24.

Original entry on oeis.org

120, 6972, 261224, 7092774, 148688232, 2503611964, 34779531480, 406309208481, 4048627642976, 34778882769216, 259669578902016, 1695618078654976, 9726900031328256, 49134911067979776, 218511510918189056, 852888183557922816
Offset: 1

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Author

Jud McCranie, Jun 23 2000

Keywords

Comments

The total number of possible positions is a(1)+...+a(24) = 500995484682338672639.
However, not all of these positions are legal, i.e. reachable from the start position. - Ralf Stephan, Sep 18 2004

Examples

			n=1: A red piece can go on any of 28 squares (it can't reside on the last row) and a red king can be on any of 32 squares. Double that to include black, total of 120.
		

References

  • Jonathan Schaeffer, N. Burch, Yngvi Bjornsson, Akihiro Kishimoto, Martin Muller, Rob Lake, Paul Lu and Steve Sutphen. "Checkers Is Solved", Science, Vol. 317, September 14, 2007, pp. 1518-1522.
  • Jonathan Schaeffer, Yngvi Bjornsson, N. Burch, Akihiro Kishimoto, Martin Muller, Rob Lake, Paul Lu and Steve Sutphen. Solving Checkers, International Joint Conference on Artificial Intelligence (IJCAI), pp. 292-297, 2005. Distinguished Paper Prize.

Crossrefs

A133803(n) = floor log a(n).
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