cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

Showing 1-5 of 5 results.

A103158 (1/2)*number of regular tetrahedra that can be formed using the points in an (n+1) X (n+1) X (n+1) lattice cube.

Original entry on oeis.org

1, 9, 36, 104, 257, 549, 1058, 1896, 3199, 5145, 7926, 11768, 16967, 23859, 32846, 44378, 58977, 77215, 99684, 126994, 159963, 199443, 246304, 301702, 366729, 442587, 530508, 631820, 748121, 880941, 1031930, 1202984, 1395927, 1612655, 1855676, 2127122, 2429577
Offset: 1

Views

Author

Hugo Pfoertner, Feb 08 2005

Keywords

Examples

			a(1)=1 because there are 2 ways to form a regular tetrahedron using vertices of the unit cube: Either [(0,0,0),(0,1,1),(1,0,1),(1,1,0)] or [(1,1,1),(1,0,0),(0,1,0),(0,0,1)].
		

References

  • E. J. Ionascu, Regular tetrahedra whose vertices have integer coordinates. Acta Math. Univ. Comenian. (N.S.) 80 (2011), no. 2, 161-170; (Acta Mathematica Universitatis Comenianae) MR2835272 (2012h:11044).

Crossrefs

Cf. triangles in lattice cube: A103426, A103427, A103428, A103429, A103499, A103500; A096315 n+1 equidistant points in Z^n.
Cf. A098928.

A334881 Number of squares in 3-dimensional space whose four vertices have coordinates (x,y,z) in the set {1,...,n}.

Original entry on oeis.org

0, 0, 6, 54, 240, 810, 2274, 5304, 10752, 19992, 34854, 57774, 91200, 139338, 206394, 296832, 417120, 575556, 779238, 1037514, 1359792, 1760694, 2251362, 2845140, 3554976, 4404876, 5416278, 6605946, 7996896, 9621678, 11500962, 13667772, 16143552, 18973608, 22190406
Offset: 0

Views

Author

Peter Kagey, May 14 2020

Keywords

Comments

a(n) >= 3*n*A002415(n).

Examples

			For n = 5, one such square has vertex set {(2,1,1), (5,4,1), (4,5,5), (1,2,5)}.
		

Crossrefs

Cf. A002415 (squares in square grid), A098928 (cubes in cube grid).

Extensions

a(7)-a(12) from Pontus von Brömssen, May 15 2020
a(13)-a(20) from Peter Kagey, Jul 29 2020 via Mathematics Stack Exchange link
Terms a(21) and beyond from Zachary Kaplan, Sep 01 2020, via Mathematics Stack Exchange link

A178797 Number of regular octahedra that can be formed using the points in an (n+1)X(n+1)X(n+1) lattice cube.

Original entry on oeis.org

0, 1, 8, 32, 104, 261, 544, 1000, 1696, 2759, 4296, 6434, 9352, 13243, 18304, 24774, 32960, 43223, 55976, 71752, 90936, 113973, 141312, 173436, 210960, 254587, 305000, 364406, 432824, 511421, 600992, 702556, 817200, 946131, 1090392, 1251238
Offset: 1

Views

Author

Eugen J. Ionascu, Jun 15 2010

Keywords

Examples

			a(2)=1 because there is 1 way to form a regular octahedron using points of a {0,1,2}^3 lattice cube.
		

Crossrefs

Extensions

Edited by Ray Chandler, Jul 27 2010

A338791 a(n) is the number of Platonic solids in three dimensions with all vertices (x,y,z) in the set {1,2,...,n}^3.

Original entry on oeis.org

0, 0, 3, 28, 116, 340, 847, 1832, 3570, 6440, 10889, 17518, 26966, 40002, 57601, 80868, 111186, 150032, 199147, 260456, 336080, 428290, 539709, 673130, 831436, 1018154, 1237155, 1492352, 1787780, 2129250, 2521323, 2969584, 3479302, 4056636, 4707661, 5438808
Offset: 0

Views

Author

Peter Kagey, Dec 05 2020

Keywords

Comments

Dodecahedra and icosahedra with integer coordinates cannot be formed in Euclidean space (of any dimension) because pentagons with integer coordinates cannot be formed in Euclidean space, and both polyhedra contain a subset of vertices that form a pentagon. Therefore, this sequence counts the regular tetrahedra, cubes, and octahedra in the bounded cubic lattice.

Crossrefs

Cf. A098928 (cubes), A103158 (tetrahedra), A178797 (octahedra), A338323 (regular polygons).

Formula

a(n) = A098928(n) + 2*A103158(n-1) + A178797(n-1) for n >= 2.

A385023 Number of cuboids (rectangular prisms) that can be formed from the points of Z^3 (a cubical grid of n X n X n points).

Original entry on oeis.org

0, 1, 36, 372, 2032, 8107, 24986, 66688, 155896, 332657, 653708, 1216076, 2135220, 3604679, 5845214, 9160864, 13947880, 20778029, 30205036, 43114824, 60340252, 83145027, 112870514, 151270988, 199965096, 261491409
Offset: 1

Views

Author

Keith F. Lynch, Jun 15 2025

Keywords

Comments

Skew cuboids are allowed. The number of orthogonal cuboids is simply binomial(n, 2)^3.
The first 15 terms were independently computed by Keith Lynch and Michael Beeler. Terms 16 through 26 are from Michael Beeler.

Examples

			The only solution for n=2 is:
  0,0,0; 0,0,1; 0,1,0; 0,1,1; 1,0,0; 1,0,1; 1,1,0; 1,1,1
The 36 solutions for n=3 are:
  0,0,0; 0,0,1; 0,1,0; 0,1,1; 2,0,0; 2,0,1; 2,1,0; 2,1,1
  0,0,0; 0,0,1; 0,2,0; 0,2,1; 1,0,0; 1,0,1; 1,2,0; 1,2,1
  0,0,0; 0,0,1; 0,2,0; 0,2,1; 2,0,0; 2,0,1; 2,2,0; 2,2,1
  0,0,0; 0,0,2; 0,1,0; 0,1,2; 1,0,0; 1,0,2; 1,1,0; 1,1,2
  0,0,0; 0,0,2; 0,1,0; 0,1,2; 2,0,0; 2,0,2; 2,1,0; 2,1,2
  0,0,0; 0,0,2; 0,2,0; 0,2,2; 1,0,0; 1,0,2; 1,2,0; 1,2,2
  0,0,1; 0,0,2; 0,1,1; 0,1,2; 2,0,1; 2,0,2; 2,1,1; 2,1,2
  0,0,1; 0,0,2; 0,2,1; 0,2,2; 1,0,1; 1,0,2; 1,2,1; 1,2,2
  0,0,1; 0,0,2; 0,2,1; 0,2,2; 2,0,1; 2,0,2; 2,2,1; 2,2,2
  0,0,1; 0,1,0; 0,1,2; 0,2,1; 1,0,1; 1,1,0; 1,1,2; 1,2,1
  0,0,1; 0,1,0; 0,1,2; 0,2,1; 2,0,1; 2,1,0; 2,1,2; 2,2,1
  0,0,1; 0,1,1; 1,0,0; 1,0,2; 1,1,0; 1,1,2; 2,0,1; 2,1,1
  0,0,1; 0,2,1; 1,0,0; 1,0,2; 1,2,0; 1,2,2; 2,0,1; 2,2,1
  0,1,0; 0,1,1; 0,2,0; 0,2,1; 2,1,0; 2,1,1; 2,2,0; 2,2,1
  0,1,0; 0,1,1; 1,0,0; 1,0,1; 1,2,0; 1,2,1; 2,1,0; 2,1,1
  0,1,0; 0,1,2; 0,2,0; 0,2,2; 1,1,0; 1,1,2; 1,2,0; 1,2,2
  0,1,0; 0,1,2; 0,2,0; 0,2,2; 2,1,0; 2,1,2; 2,2,0; 2,2,2
  0,1,0; 0,1,2; 1,0,0; 1,0,2; 1,2,0; 1,2,2; 2,1,0; 2,1,2
  0,1,1; 0,1,2; 0,2,1; 0,2,2; 2,1,1; 2,1,2; 2,2,1; 2,2,2
  0,1,1; 0,1,2; 1,0,1; 1,0,2; 1,2,1; 1,2,2; 2,1,1; 2,1,2
  0,1,1; 0,2,1; 1,1,0; 1,1,2; 1,2,0; 1,2,2; 2,1,1; 2,2,1
  1,0,0; 1,0,1; 1,2,0; 1,2,1; 2,0,0; 2,0,1; 2,2,0; 2,2,1
  0,1,1; 0,2,1; 1,1,0; 1,1,2; 1,2,0; 1,2,2; 2,1,1; 2,2,1
  1,0,0; 1,0,1; 1,2,0; 1,2,1; 2,0,0; 2,0,1; 2,2,0; 2,2,1
  1,0,0; 1,0,2; 1,1,0; 1,1,2; 2,0,0; 2,0,2; 2,1,0; 2,1,2
  1,0,0; 1,0,2; 1,2,0; 1,2,2; 2,0,0; 2,0,2; 2,2,0; 2,2,2
  1,0,1; 1,0,2; 1,2,1; 1,2,2; 2,0,1; 2,0,2; 2,2,1; 2,2,2
  1,0,1; 1,1,0; 1,1,2; 1,2,1; 2,0,1; 2,1,0; 2,1,2; 2,2,1
  1,1,0; 1,1,2; 1,2,0; 1,2,2; 2,1,0; 2,1,2; 2,2,0; 2,2,2
  0,0,0; 0,0,1; 0,1,0; 0,1,1; 1,0,0; 1,0,1; 1,1,0; 1,1,1
  0,0,1; 0,0,2; 0,1,1; 0,1,2; 1,0,1; 1,0,2; 1,1,1; 1,1,2
  0,1,0; 0,1,1; 0,2,0; 0,2,1; 1,1,0; 1,1,1; 1,2,0; 1,2,1
  0,1,1; 0,1,2; 0,2,1; 0,2,2; 1,1,1; 1,1,2; 1,2,1; 1,2,2
  1,0,0; 1,0,1; 1,1,0; 1,1,1; 2,0,0; 2,0,1; 2,1,0; 2,1,1
  1,0,1; 1,0,2; 1,1,1; 1,1,2; 2,0,1; 2,0,2; 2,1,1; 2,1,2
  1,1,0; 1,1,1; 1,2,0; 1,2,1; 2,1,0; 2,1,1; 2,2,0; 2,2,1
  1,1,1; 1,1,2; 1,2,1; 1,2,2; 2,1,1; 2,1,2; 2,2,1; 2,2,2
		

Crossrefs

Cf. A098928.
Showing 1-5 of 5 results.