OFFSET
1,3
COMMENTS
A centered hexagonal grid of size n is a grid with A003215(n-1) points forming a hexagonal lattice.
LINKS
Eric Weisstein's World of Mathematics, Hex Number.
Eric Weisstein's World of Mathematics, Obtuse Triangle.
EXAMPLE
For n = 2 the only kind of non-congruent obtuse triangles is the following:
/* *
. . *
\. .
CROSSREFS
KEYWORD
nonn
AUTHOR
Martin Renner, Apr 17 2014
EXTENSIONS
a(7) from Martin Renner, May 31 2014
a(8)-a(14) from Giovanni Resta, May 31 2014
More terms from Bert Dobbelaere, Oct 17 2022
STATUS
approved