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A125679 Number of combinatorial 2-manifolds with n vertices. 0
9, 44, 655, 42426, 11590894, 12561206794 (list; graph; refs; listen; history; text; internal format)
OFFSET

7,1

LINKS

Table of n, a(n) for n=7..12.

Basudeb Datta, Minimal Triangulations of Manifolds, 25 Jan 2007, arXiv:math/0701735

EXAMPLE

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 forty-four 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.

CROSSREFS

Sequence in context: A084016 A221508 A301397 * A037207 A225488 A096688

Adjacent sequences:  A125676 A125677 A125678 * A125680 A125681 A125682

KEYWORD

hard,more,nonn

AUTHOR

Jonathan Vos Post, Jan 30 2007

EXTENSIONS

Replaced arXiv URL by non-cached version - R. J. Mathar, Oct 30 2009

STATUS

approved

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Last modified November 14 09:51 EST 2019. Contains 329111 sequences. (Running on oeis4.)