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A166742
Arises in enumeration of three-dimensional crystallographic Seifert and co-Seifert fibrations.
0
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
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
KEYWORD
nonn,fini,full
AUTHOR
Jonathan Vos Post, Oct 21 2009
STATUS
approved