A166742 Arises in enumeration of three-dimensional crystallographic Seifert and co-Seifert fibrations.

1, 4, 7, 9, 19, 29, 33, 76, 144, 169

Offset: 1

Author

Jonathan Vos Post, Oct 21 2009

Keywords

• nonn
• fini
• full

Comments

p.25 of Ratcliffe: "The information in Table 1 was obtained by computer calculations. Finally, the 10 closed flat space forms in Table 1 have IT numbers 1,4,7,9,19,29,33,76,144,169."

The "IT numbers" here are merely numbers of certain 3D space groups in the International Tables for Crystallography. Thus, the terms of this sequence don't have their own mathematical meaning. - Andrey Zabolotskiy, Jul 05 2017

Links

• John G. Ratcliffe and Steven T. Tschantz, Fibered orbifolds and crystallographic groups, arXiv:0804.0427 [math.GT], 2008-2009.

Crossrefs

Cf. A004029.