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A229757
Numbers n such that no convex hexagon exists that can be dissected into n congruent equilateral triangles.
2
1, 2, 3, 4, 5, 7, 8, 9, 11, 12, 15, 17, 20, 21, 23, 29, 36, 39, 41, 44, 84
OFFSET
1,2
COMMENTS
Numbers not expressible as k = 2*(a*c + b*c + b*d) - (a-d)^2 with a,b,c,d >= 1, a < c+d, d < a+b.
See the Hertel paper for the finiteness proof.
LINKS
Eike Hertel, Reguläre Dreieckspflasterungen konvexer Polygone, Jenaer Schriften zur Mathematik und Informatik, Math/Inf/01/13, 2013 (preprint).
Eike Hertel, Christian Richter, Tiling Convex Polygons with Congruent Equilateral Triangles, Discrete Comput Geom (2014) 51:753-759.
CROSSREFS
Cf. A229461 (Pentagon exception numbers).
Sequence in context: A050730 A288221 A346782 * A319272 A366142 A141819
KEYWORD
nonn,fini,full
AUTHOR
Suggested by Eike Hertel, Hugo Pfoertner, Sep 28 2013
STATUS
approved