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Arises in enumeration of three-dimensional crystallographic Seifert and co-Seifert fibrations.
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%I #11 Aug 02 2022 13:01:04

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

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

%C 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."

%C 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

%H John G. Ratcliffe and Steven T. Tschantz, <a href="http://arxiv.org/abs/0804.0427">Fibered orbifolds and crystallographic groups</a>, arXiv:0804.0427 [math.GT], 2008-2009.

%Y Cf. A004029.

%K nonn,fini,full

%O 1,2

%A _Jonathan Vos Post_, Oct 21 2009