Function Repository Resource:

# OrderedTupleFromIndex

Get the ordered tuple with the given index and length

Contributed by: Ed Pegg Jr
 ResourceFunction["OrderedTupleFromIndex"][index,len] returns an ordered tuple of length len with given index.

## Details and Options

Ordered tuples are considered to be lists {a1,a2,,ak} such that the ai are non-negative and non-decreasing.
For any ordered tuple, a unique index n can be defined via .
For example, subset {1, 2, 2} has index .

## Examples

### Basic Examples (3)

The following ordered 3-tuple sequence can be extended to infinity:

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The function can return ordered tuples of a large index:

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The function can return ordered tuples of a given index for various lengths:

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### Scope (3)

Here are some ordered 2-tuples with their indices to show their structure:

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The ordered 2-tuple {4,4} has an index of :

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Use this to recover the tuple:

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The structure of ordered 3-tuples in 3D:

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### Properties and Relations (3)

Use Tuples to produce ordered 3-tuples:

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The same sequence of ordered 3-tuples can be obtained from ordered Subsets:

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OrderedTupleFromIndex returns the same ordered tuples in the same sequence:

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## Version History

• 1.0.0 – 06 December 2019