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A374898
Index of the closure of a triangle group Delta, associated with billiards in a regular n-gon, in the adelic group Gamma = SL_2(O), where O is the profinite completion of Z[zeta + zeta^{-1}] and zeta is the n-th root of unity.
1
1, 3, 72, 8, 144, 24, 112, 288, 23808, 8, 322560, 6912, 6528, 3072, 62668800, 896, 904200192, 1536, 199680, 2856960, 191219367936, 1024, 10995105792, 54190080, 636289024, 294912, 621186153185280, 1088, 9270541147963392, 100663296, 8313372672, 18048614400, 2010535428096
OFFSET
3,2
LINKS
Frank Calegari, The adelic closure of triangle groups, arXiv:2407.20374 [math.NT], 2024. See p. 3.
Frank Calegari, PARI program
CROSSREFS
Sequence in context: A073589 A089537 A321530 * A062074 A290004 A332188
KEYWORD
nonn
AUTHOR
Michel Marcus, Jul 31 2024
EXTENSIONS
More terms from Michel Marcus, Aug 13 2024
STATUS
approved