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So many ways.... (Posted on 2013-03-21) Difficulty: 3 of 5
Consider all "integer" points in the 1st Quadrant, i.e. North-East part of the coordinates system.
How many lattice paths from (0,0) to (b,a) exist if only east (1,0), north (0,1), and northeast (1,1) steps are allowed?

Provide a general recurrence formula, supported by few samples, say all (a,b) points between (0,0) and (6,6).

What can be said about the numbers thus obtained?
Try to formulate a direct formula for the integer points on the y=x line, i.e. D(m,m)=...

  Submitted by Ady TZIDON    
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Solution: (Hide)
Compare:
1. A001850 and various web entries about Central Delannoy numbers
2. Charlie's solution.

Comments: ( You must be logged in to post comments.)
  Subject Author Date
re: solutionDej Mar2013-03-22 06:06:00
SolutionsolutionCharlie2013-03-21 16:11:36
Some short answersJer2013-03-21 14:55:59
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