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A018228 Numbers n such that normalizer of Gamma_0(n) is triangle group (2,3,inf). 3
1, 4, 9, 16, 36, 64, 144, 576 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

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.

LINKS

Table of n, a(n) for n=1..8.

CROSSREFS

Cf. A018229, A018230, A018231.

Sequence in context: A117218 A226076 A272711 * A204503 A138858 A076967

Adjacent sequences:  A018225 A018226 A018227 * A018229 A018230 A018231

KEYWORD

nonn,fini,full

AUTHOR

N. J. A. Sloane.

EXTENSIONS

Keywords added by Sean A. Irvine, Feb 05 2019

STATUS

approved

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Last modified October 21 16:20 EDT 2019. Contains 328302 sequences. (Running on oeis4.)