MathGroup Archive 1999

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Numbers problem


It's called "Langford's Problem". It first appeared around 1958 and was
popularized by Martin Gardner ten years later.

Here are the number of *pairs* of solutions:

 3:               1
 4:               1

 7:              26
 8:             150

11:          17,792
12:         108,144

15:      39,809,640
16:     326,721,800

19: 256,814,891,280
20:               ?

The case for n = 19 was just solved a few months ago: It took 4 people two
months of computing!

See: http://www.lclark.edu/~miller/langford.html




  • Prev by Date: Asking you how to...
  • Next by Date: RE: Automatic Display in MatrixForm
  • Previous by thread: Re: Numbers problem
  • Next by thread: Re: Re: Numbers problem