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A250098
Number of triangles in minimal triangulation of the orientable closed surface of genus n (S_n).
1
8, 14, 24, 20, 22, 24, 24, 26, 28, 28, 30, 30, 32, 32, 34, 34, 36, 36, 38, 38, 38, 40, 40, 42, 42, 42, 44, 44, 44, 46, 46, 46, 48, 48, 48, 48, 50, 50, 50, 52, 52, 52, 52, 54, 54, 54, 54, 56, 56, 56, 56, 58, 58, 58, 58, 60, 60, 60, 60, 62, 62
OFFSET
0,1
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), 121-154.
Ringel, Gerhard. Wie man die geschlossenen nichtorientierbaren Flächen in möglichst wenig Dreiecke zerlegen kann. (German) Math. Ann. 130 (1955), 317--326. MR0075591 (17,774b)
FORMULA
a(n) = 2*ceiling((7 + sqrt(1+48*n))/2) + 4*(n-1), except a(2) = 24.
CROSSREFS
See A123869 for number of vertices in a minimal triangulation.
Sequence in context: A325302 A053668 A218145 * A155156 A275898 A248427
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Nov 12 2014
STATUS
approved