

A123869


Order of minimal triangulation of the orientable closed surface of genus n (S_n).


1



4, 7, 10, 10, 11, 12, 12, 13, 14, 14, 15, 15, 16, 16, 17, 17, 18, 18, 19, 19, 19, 20, 20, 21, 21, 21, 22, 22, 22, 23, 23, 23, 24, 24, 24, 24, 25, 25, 25, 26, 26, 26, 26, 27, 27, 27, 27, 28, 28, 28, 28, 29, 29, 29, 29, 30, 30, 30, 30, 31, 31, 31, 31, 31, 32, 32, 32, 32, 33, 33, 33, 33, 33
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OFFSET

0,1


COMMENTS

Number of vertices in a triangulation of the orientable closed surface S_n of genus n that has the smallest number of vertices.


REFERENCES

J. L. Gross and J. Yellen, eds., Handbook of Graph Theory, CRC Press, 2004; p. 742, Fact F19.
M. Jungerman and G. Ringel, Minimal triangulations on orientable surfaces, Acta Math. 145 (1980), 121154.
Ringel, Gerhard. Wie man die geschlossenen nichtorientierbaren Flächen in möglichst wenig Dreiecke zerlegen kann. (German) Math. Ann. 130 (1955), 317326. MR0075591 (17,774b)


LINKS

Table of n, a(n) for n=0..72.


FORMULA

Ceil( (7+sqrt(1+48*n))/2 ), except a(2) = 10.


CROSSREFS

See A250098 for number of triangles in a minimal triangulation.
Sequence in context: A118517 A282848 A093465 * A072125 A223024 A275340
Adjacent sequences: A123866 A123867 A123868 * A123870 A123871 A123872


KEYWORD

nonn


AUTHOR

N. J. A. Sloane, Nov 19 2006


STATUS

approved



