7,1

Basudeb Datta, Minimal Triangulations of Manifolds, 25 Jan 2007.

a(7) = 9 because there are exactly nine 7-vertex combinatorial 2-manifolds, five of which triangulate the 2-sphere S^2, three of which triangulate RP^2, and one triangulates S^1 X S^1.

a(8) = 44 because there are exactly fortyfour 8-vertex combinatorial 2-manifolds, one of which consists of two copies of S(_4)^2, fourteen of which triangulate the 2-sphere S^2, sixteen of which triangulate RP^2, seven triangulate S^1 X S^1, and six triangulate the Klein bottle.

Sequence in context: A099867 A104470 A084016 this_sequence A037207 A096688 A124983

Adjacent sequences: A125676 A125677 A125678 this_sequence A125680 A125681 A125682

hard,nonn

Jonathan Vos Post (jvospost2(AT)yahoo.com), Jan 30 2007