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A018229
Numbers n such that normalizer of Gamma_0(n) is triangle group (2,4,inf).
3
2, 8, 18, 32, 72, 128, 288, 1152
OFFSET
1,1
REFERENCES
M. Akbas and D. Singerman, The signature of the normalizer Gamma_0(N), in Graphs, Combinatorics and Geometry, ed. Liebeck and Saxl, LMSLNS 165, Cambridge Univ. Press, 1992, 77-86.
CROSSREFS
KEYWORD
nonn,fini,full
AUTHOR
EXTENSIONS
Keywords added by Sean A. Irvine, Feb 05 2019
STATUS
approved