

A261765


Triangle read by rows: T(n,k) is the number of subpermutations of an nset, whose orbits are each of size at most k with at least one orbit of size exactly k, and without fixed points. Equivalently, T(n,k) is the number of partial derangements of an nset each of whose orbits is of size at most k with at least one orbit of size exactly k, and without fixed points.


5



1, 1, 0, 1, 0, 3, 1, 0, 9, 8, 1, 0, 45, 32, 30, 1, 0, 165, 320, 150, 144, 1, 0, 855, 2240, 1800, 864, 840, 1, 0, 3843, 17360, 18900, 12096, 5880, 5760, 1, 0, 21819, 146048, 195300, 145152, 94080, 46080, 45360, 1, 0, 114075, 1256192, 2120580, 1959552, 1270080, 829440, 408240, 403200
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OFFSET

0,6


COMMENTS

T(n,n) is A261766. Sum of rows is A144085.


REFERENCES

A. Laradji and A. Umar, On the number of subpermutations with fixed orbit size, Ars Combinatoria, 109 (2013), 447460.


LINKS

Table of n, a(n) for n=0..54.


FORMULA

T(n,k) = A261762(n,k)  A261762(n,k1).


EXAMPLE

T(n,1) = 0 because there is no (partial) derangement with an orbit of size 1.
T(3,2) = 9 because there are 9 subpermutations on {1,2,3}, whose orbits are each of size at most 2 with at least one orbit of size exactly 2, and without fixed points, namely: (1 2 > 2 1), (1 3 > 3 1), (2 3 > 3 2), (1>2), (1>3), (2>1), (2>3), (3>1), (3>2).
Triangle starts:
1;
1, 0;
1, 0, 3;
1, 0, 9, 8;
1, 0, 45, 32, 30;
1, 0, 165, 320, 150, 144;
1, 0, 855, 2240, 1800, 864, 840;
...


CROSSREFS

Cf. A157400, A261762, A261763, A261764, A261766, A261767.
Sequence in context: A126178 A094753 A221713 * A143398 A202995 A191578
Adjacent sequences: A261762 A261763 A261764 * A261766 A261767 A261768


KEYWORD

nonn,tabl


AUTHOR

Samira Stitou, Sep 21 2015


EXTENSIONS

More terms from Alois P. Heinz, Nov 04 2015


STATUS

approved



