

A091071


Number of normalizers of subgroups of the symmetric group on n points.


0



1, 1, 1, 2, 4, 5, 12, 19, 42, 72, 127, 196, 500
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OFFSET

0,4


REFERENCES

G. Pfeiffer, Counting Transitive Relations, preprint, 2004.


LINKS

Table of n, a(n) for n=0..12.
G. Pfeiffer, Subgroups.
G. Pfeiffer, Counting Transitive Relations, Journal of Integer Sequences, Vol. 7 (2004), Article 04.3.2.


EXAMPLE

a(3)=2 because of the 4 (conjugacy classes of) subgroups of Sym(3) only 2 (Sym(2) and Sym(3)) are normalizers of subgroups.


CROSSREFS

Cf. A000638 (subgroups of Sym(n)), A091070 (stabilizers of partial orders).
Sequence in context: A090847 A056984 A117556 * A050599 A102932 A128457
Adjacent sequences: A091068 A091069 A091070 * A091072 A091073 A091074


KEYWORD

hard,nonn


AUTHOR

Goetz Pfeiffer (goetz.pfeiffer(AT)nuigalway.ie), Jan 21 2004


STATUS

approved



