How many sets of 3 numbers can be formed from the numbers {1,2,3,..,20} if no 2 consecutive numbers are set to be in a set?

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- April 8th 2008, 09:42 AMlacy1104Permutations and Combinations
How many sets of 3 numbers can be formed from the numbers {1,2,3,..,20} if no 2 consecutive numbers are set to be in a set?

- April 8th 2008, 10:40 AMPlato
The string “00001010000000100000”, three 1's & seventeen 0's, can be used to represent the subset {5,7,15}. In fact, any rearrangement of the string

**with no adjacent 1’s**can represent a subset of three with**no consecutive**integers.

How many such rearrangements are there?