login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A269747 Number of regular tetrahedra in an n-node-per-edge tetrahedral grid. 4
0, 0, 1, 5, 16, 39, 80, 155, 281, 476, 760, 1154, 1686, 2394, 3331, 4551, 6110, 8065, 10486, 13461, 17079, 24130, 26606, 32726, 39928, 48360, 58183, 69573, 82708, 97767, 114930, 134387, 156329, 180960, 208506, 239230, 273444, 311486, 353709, 400467, 452136, 509093, 571716, 640393, 715537 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,4

COMMENTS

Number of ways to choose 4 points forming a regular tetrahedron out of the binomial(n+2,3) points in a regular tetrahedral grid.

The tetrahedra defined by the four points may have any orientation.

Similar to A216173, which differs from the present sequence in a mysterious way.

LINKS

Table of n, a(n) for n=0..44.

FORMULA

It would be nice to have a g.f. - N. J. A. Sloane, Mar 21 2016

CROSSREFS

Cf. A000332 (2-D version), A216173, A270805, A270806.

Sequence in context: A082190 A155965 A216173 * A011863 A027085 A099452

Adjacent sequences:  A269744 A269745 A269746 * A269748 A269749 A269750

KEYWORD

nonn

AUTHOR

Warren D. Smith, Mar 21 2016; more terms Mar 23 2016

STATUS

approved

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 19 12:29 EDT 2018. Contains 316360 sequences. (Running on oeis4.)