%I #9 Nov 30 2019 01:31:09
%S 8,14,24,20,22,24,24,26,28,28,30,30,32,32,34,34,36,36,38,38,38,40,40,
%T 42,42,42,44,44,44,46,46,46,48,48,48,48,50,50,50,52,52,52,52,54,54,54,
%U 54,56,56,56,56,58,58,58,58,60,60,60,60,62,62
%N Number of triangles in minimal triangulation of the orientable closed surface of genus n (S_n).
%D J. L. Gross and J. Yellen, eds., Handbook of Graph Theory, CRC Press, 2004; p. 742, Fact F19.
%D M. Jungerman and G. Ringel, Minimal triangulations on orientable surfaces, Acta Math. 145 (1980), 121-154.
%D Ringel, Gerhard. Wie man die geschlossenen nichtorientierbaren Flächen in möglichst wenig Dreiecke zerlegen kann. (German) Math. Ann. 130 (1955), 317--326. MR0075591 (17,774b)
%F a(n) = 2*ceiling((7 + sqrt(1+48*n))/2) + 4*(n-1), except a(2) = 24.
%Y See A123869 for number of vertices in a minimal triangulation.
%K nonn
%O 0,1
%A _N. J. A. Sloane_, Nov 12 2014