

A262494


Triangle read by rows: T(n,k) (n>=1, 0<=k<n) is the number of permutations of n things that require k stacksorts.


0



1, 1, 1, 1, 4, 1, 1, 13, 8, 2, 1, 41, 49, 23, 6, 1, 131, 276, 198, 90, 24
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OFFSET

1,5


COMMENTS

It appears that no recurrence or g.f. is known.  N. J. A. Sloane, Oct 13 2015


LINKS

Table of n, a(n) for n=1..21.
FindStat  Combinatorial Statistic Finder, The number of stacksorts needed to sort a permutation


FORMULA

T(n,0) = 1, T(n,1) = A000108(n)  1.  Joerg Arndt, Sep 27 2015


EXAMPLE

Triangle begins:
1,
1, 1,
1, 4, 1,
1, 13, 8, 2,
1, 41, 49, 23, 6,
1,131,276,198,90,24,
...


CROSSREFS

Sequence in context: A140070 A158815 A101275 * A039755 A247502 A047874
Adjacent sequences: A262491 A262492 A262493 * A262495 A262496 A262497


KEYWORD

nonn,tabl,more


AUTHOR

Christian Stump, Sep 24 2015


EXTENSIONS

Definition edited by N. J. A. Sloane, Oct 13 2015
Added more terms Christian Stump, Oct 19 2015


STATUS

approved



