|
|
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
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
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
|
|
|
CROSSREFS
|
Cf. A229461 (Pentagon exception numbers).
|
|
KEYWORD
|
nonn,fini,full
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|