MidPointsOfOccurrencesOf321 on Permutation
Positions that are the middle of a 321 occurrence: neither a left-to-right maximum nor a right-to-left minimum.
Called as CombinatorialStat(x, "MidPointsOfOccurrencesOf321"). The head's page has its examples.
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FindStat St000371
The number of mid points of decreasing subsequences of length 3 in a permutation.
| Object | Value |
|---|---|
[] | 0 |
[1] | 0 |
[1,2] | 0 |
[2,1] | 0 |
[1,2,3] | 0 |
[1,3,2] | 0 |
[2,1,3] | 0 |
[2,3,1] | 0 |
Data from FindStat, the combinatorial statistic finder; the page at findstat.org/St000371 has the rest.