PartsEqualOne

Parts equal to 1.

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PartsEqualOne(partition)Parts equal to 1.

Typed signatures

Type	Package	Applies
(composition | integer_partition) -> number	combinatorics	always

Domain: Partition statistics

Details

• Defined over IntegerPartition as an expression in _x, evaluated by compute-engine — the definition IS the implementation.
• Takes a IntegerPartition and nothing else — it reads values against their positions, or walks the orbits, so it needs the bijection. Applying it to a bare list is a type error, not a wrong answer.

Definition

Epsil, as the implementation runs it.

on IntegerPartition, over _x

0 if Length(_x) < 1 else Count(Filter(
                                       Range(1, Length(_x)),
                                       Function(_x[i] == 1, i),
                                     ))

Examples

Basic #

the partition $4 + 2 + 1$ of $7$

live ↗

In$\mathrm{PartsEqualOne}({\operatorname{IntegerPartition}}([4, 2, 1]))$Out$1$

the partition $3 + 3 + 1$ of $7$

live ↗

In$\mathrm{PartsEqualOne}({\operatorname{IntegerPartition}}([3, 3, 1]))$Out$1$

the composition $[2,1,3,1,1]$

live ↗

In$\mathrm{PartsEqualOne}({\operatorname{IntegerComposition}}([2, 1, 3, 1, 1]))$Out$3$

Properties #

FindStat's value for [1]

live ↗

In$\mathrm{CombinatorialStat}({\operatorname{IntegerPartition}}([1]), \text{PartsEqualOne})$Out$1$

Known value · FindStat St000475

FindStat's value for [2]

live ↗

In$\mathrm{CombinatorialStat}({\operatorname{IntegerPartition}}([2]), \text{PartsEqualOne})$Out$0$

Known value · FindStat St000475

FindStat's value for [3]

live ↗

In$\mathrm{CombinatorialStat}({\operatorname{IntegerPartition}}([3]), \text{PartsEqualOne})$Out$0$

Known value · FindStat St000475

About

Examples	6
Crosswalk	FindStat