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

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

Offset

1,2

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

Table of n, a(n) for n=1..10.

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

Crossrefs

Cf. A004029.

Sequence in context: A359016 A281144 A103073 * A346554 A022541 A330695

Adjacent sequences: A166739 A166740 A166741 * A166743 A166744 A166745

Keyword

nonn,fini,full

Author

Jonathan Vos Post, Oct 21 2009

Status

approved