A091071 Number of normalizers of subgroups of the symmetric group on n points.

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

Offset: 0

Author

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

Keywords

• hard
• nonn

Examples

			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.
		

References

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

Links

• G. Pfeiffer, Subgroups.
• G. Pfeiffer, Counting Transitive Relations, Journal of Integer Sequences, Vol. 7 (2004), Article 04.3.2.

Crossrefs

Cf. A000638 (subgroups of Sym(n)), A091070 (stabilizers of partial orders).