A018230 Numbers n such that normalizer of Gamma_0(n) is triangle group (2,6,inf).

3, 12, 27, 48, 108, 192, 432, 1728

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.

Links

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

Crossrefs

Cf. A018229, A018228, A018231.

Sequence in context: A074630 A033428 A213486 * A058034 A294416 A187273

Adjacent sequences: A018227 A018228 A018229 * A018231 A018232 A018233

Keyword

nonn,fini,full

Author

N. J. A. Sloane.

Extensions

Corrected Apr 15 1997.

Keywords added by Sean A. Irvine, Feb 05 2019

Status

approved