login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A241233 Number of right triangles, distinct up to congruence, on a centered hexagonal grid of size n. 3
0, 1, 5, 13, 25, 42, 62, 86, 115, 150, 191, 234, 282, 334, 395, 455, 526, 601, 677, 762, 855, 947, 1045, 1152, 1261, 1378, 1498, 1619, 1757, 1900, 2041, 2176, 2334, 2507, 2661, 2838, 3011, 3174, 3379, 3577, 3773, 3967, 4179, 4389, 4618, 4848, 5090, 5311, 5559, 5792, 6068 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

A centered hexagonal grid of size n is a grid with A003215(n-1) points forming a hexagonal lattice.

LINKS

Table of n, a(n) for n=1..51.

Eric Weisstein's World of Mathematics, Hex Number.

Eric Weisstein's World of Mathematics, Right Triangle.

FORMULA

a(n) = A241231(n) - A241232(n) - A241234(n).

EXAMPLE

For n = 2 the only kind of non-congruent right triangles is the following:

/. *

* . *

\. .

CROSSREFS

Cf. A189979, A241225.

Sequence in context: A098483 A147205 A146875 * A064276 A240001 A301685

Adjacent sequences: A241230 A241231 A241232 * A241234 A241235 A241236

KEYWORD

nonn

AUTHOR

Martin Renner, Apr 17 2014

EXTENSIONS

a(7) from Martin Renner, May 31 2014

a(8)-a(21) from Giovanni Resta, May 31 2014

More terms from Bert Dobbelaere, Oct 17 2022

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified February 8 15:28 EST 2023. Contains 360149 sequences. (Running on oeis4.)