Identifier
- St000501: Permutations ⟶ ℤ
Values
[1] => 1
[1,2] => 1
[2,1] => 2
[1,2,3] => 1
[1,3,2] => 1
[2,1,3] => 2
[2,3,1] => 3
[3,1,2] => 3
[3,2,1] => 3
[1,2,3,4] => 1
[1,2,4,3] => 1
[1,3,2,4] => 1
[1,3,4,2] => 1
[1,4,2,3] => 1
[1,4,3,2] => 1
[2,1,3,4] => 2
[2,1,4,3] => 2
[2,3,1,4] => 3
[2,3,4,1] => 4
[2,4,1,3] => 4
[2,4,3,1] => 4
[3,1,2,4] => 3
[3,1,4,2] => 4
[3,2,1,4] => 3
[3,2,4,1] => 4
[3,4,1,2] => 4
[3,4,2,1] => 4
[4,1,2,3] => 4
[4,1,3,2] => 4
[4,2,1,3] => 4
[4,2,3,1] => 4
[4,3,1,2] => 4
[4,3,2,1] => 4
[1,2,3,4,5] => 1
[1,2,3,5,4] => 1
[1,2,4,3,5] => 1
[1,2,4,5,3] => 1
[1,2,5,3,4] => 1
[1,2,5,4,3] => 1
[1,3,2,4,5] => 1
[1,3,2,5,4] => 1
[1,3,4,2,5] => 1
[1,3,4,5,2] => 1
[1,3,5,2,4] => 1
[1,3,5,4,2] => 1
[1,4,2,3,5] => 1
[1,4,2,5,3] => 1
[1,4,3,2,5] => 1
[1,4,3,5,2] => 1
[1,4,5,2,3] => 1
[1,4,5,3,2] => 1
[1,5,2,3,4] => 1
[1,5,2,4,3] => 1
[1,5,3,2,4] => 1
[1,5,3,4,2] => 1
[1,5,4,2,3] => 1
[1,5,4,3,2] => 1
[2,1,3,4,5] => 2
[2,1,3,5,4] => 2
[2,1,4,3,5] => 2
[2,1,4,5,3] => 2
[2,1,5,3,4] => 2
[2,1,5,4,3] => 2
[2,3,1,4,5] => 3
[2,3,1,5,4] => 3
[2,3,4,1,5] => 4
[2,3,4,5,1] => 5
[2,3,5,1,4] => 5
[2,3,5,4,1] => 5
[2,4,1,3,5] => 4
[2,4,1,5,3] => 5
[2,4,3,1,5] => 4
[2,4,3,5,1] => 5
[2,4,5,1,3] => 5
[2,4,5,3,1] => 5
[2,5,1,3,4] => 5
[2,5,1,4,3] => 5
[2,5,3,1,4] => 5
[2,5,3,4,1] => 5
[2,5,4,1,3] => 5
[2,5,4,3,1] => 5
[3,1,2,4,5] => 3
[3,1,2,5,4] => 3
[3,1,4,2,5] => 4
[3,1,4,5,2] => 5
[3,1,5,2,4] => 5
[3,1,5,4,2] => 5
[3,2,1,4,5] => 3
[3,2,1,5,4] => 3
[3,2,4,1,5] => 4
[3,2,4,5,1] => 5
[3,2,5,1,4] => 5
[3,2,5,4,1] => 5
[3,4,1,2,5] => 4
[3,4,1,5,2] => 5
[3,4,2,1,5] => 4
[3,4,2,5,1] => 5
[3,4,5,1,2] => 5
[3,4,5,2,1] => 5
[3,5,1,2,4] => 5
[3,5,1,4,2] => 5
>>> Load all 1201 entries. <<<
search for individual values
searching the database for the individual values of this statistic
/
search for generating function
searching the database for statistics with the same generating function
Description
The size of the first part in the decomposition of a permutation.
For a permutation $\pi$ of $\{1,\ldots,n\}$, this is defined to be the smallest $k > 0$ such that $\{\pi(1),\ldots,\pi(k)\} = \{1,\ldots,k\}$. This statistic is undefined for the empty permutation.
For the number of parts in the decomposition see St000056The decomposition (or block) number of a permutation..
For a permutation $\pi$ of $\{1,\ldots,n\}$, this is defined to be the smallest $k > 0$ such that $\{\pi(1),\ldots,\pi(k)\} = \{1,\ldots,k\}$. This statistic is undefined for the empty permutation.
For the number of parts in the decomposition see St000056The decomposition (or block) number of a permutation..
References
[1] Gao, A. L. L., Kitaev, S., Zhang, P. B. On pattern avoiding indecomposable permutations arXiv:1605.05490
Code
def statistic(pi):
if not pi:
return
k = 1
while sorted(pi[:k]) != [1..k]:
k += 1
return k
Created
May 19, 2016 at 15:47 by Christian Stump
Updated
Jan 07, 2021 at 21:29 by Martin Rubey
searching the database
Sorry, this statistic was not found in the database
or
add this statistic to the database – it's very simple and we need your support!