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.

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A365139 List of free polycubes in binary code (see comments), ordered first by the number of cells, then by the value of the binary code.

Original entry on oeis.org

1, 3, 7, 19, 15, 23, 39, 43, 51, 54, 1043, 31, 47, 55, 59, 87, 118, 173, 179, 182, 199, 230, 1047, 1075, 1078, 2071, 2075, 2149, 2150, 2164, 2214, 2218, 6182, 1049619, 63, 95, 119, 175, 183, 190, 207, 215, 231, 237, 238, 246, 423, 430, 438, 1055, 1079, 1083
Offset: 1

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Author

Pontus von Brömssen, Aug 23 2023

Keywords

Comments

The binary code used here is a straight-forward generalization of the binary code in A246521 to d > 2 dimensions. Order the d-tuples of nonnegative integers, first according to their sum, then colexicographically. (For the purposes of this definition, the result will be the same if we use lexicographic order instead.) Label the d-tuples 0, 1, 2, ... in this order. (For d = 3, this is the ordering of triples given by A144625.) Given a d-dimensional polyomino (represented as a finite set of integer d-tuples), consider all the d!*2^d ways of rotating/reflecting it. Translate each such rotation/reflection so that the minimum coordinate is 0 in each dimension, and add the powers of 2 with exponents equal to the labels of the d-tuples of the translation. The binary code of the polyomino (or any finite set of d-tuples) is the minimum of those sums.
Can be read as an irregular triangle, whose n-th row contains A038119(n) terms.

Examples

			Consider the pentacube consisting of a straight tricube with two monocubes attached to two adjacent faces of its middle cube. The following table shows the first few triples (with their ordinal number in front), with those triples appearing in the orientation of the pentacube that minimizes the binary code marked with an "X":
  0. 000 X
  1. 100 X
  2. 010
  3. 001
  4. 200 X
  5. 110 X
  6. 020
  7. 101 X
  8. 011
  9. 002
Consequently, the binary code of this pentacube is 2^0+2^1+2^4+2^5+2^7 = 179 = a(19).
As an irregular triangle:
  1;
  3;
  7, 19;
  15, 23, 39, 43, 51, 54, 1043;
  ...
		

Crossrefs

Cf. A038119, A144625, A246521 (2 dimensions), A365140 (4 dimensions), A365141 (5 dimensions).

A371397 Number of chiral pairs of polyominoes with n cubical cells of the regular tiling with Schläfli symbol {4,3,4}.

Original entry on oeis.org

0, 0, 0, 1, 6, 54, 416, 3111, 22898, 168460, 1242985, 9227333, 68949103, 518618196, 3925228596, 29879207817, 228630283775, 1757699977107, 13570824097968, 105182547181534, 818093724437992, 6383353614308209
Offset: 1

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Author

Robert A. Russell, Mar 21 2024

Keywords

Comments

Also called polycubes. Each member of a chiral pair is a reflection but not a rotation of the other.

Examples

			Polyominoes with cell centers at (0,0,0), (0,0,1), (0,1,1), (1,1,1) and (0,0,0), (0,1,0), (0,1,1), (1,1,1) are a chiral pair.
		

Crossrefs

Cf. A000162 (oriented), A038119 (unoriented), A007743 (achiral), A001931 (fixed).

Formula

a(n) = A000162(n) - A038119(n) = (A000162(n) - A007743(n))/2 = A038119(n) - A007743(n).

Extensions

a(17)-a(22) from John Mason, Sep 19 2024

A376797 Number of free rooted (or pointed) polycubes with n cells.

Original entry on oeis.org

1, 1, 4, 16, 90, 562, 3960, 29311, 225370, 1766974, 14030739, 112269684, 903020688
Offset: 1

Views

Author

John Mason, Oct 04 2024

Keywords

Examples

			There are 2 polycubes of size 3, each having 2 distinct cells. Therefore a(3)=4.
For further examples, see link.
		

Crossrefs

A377128 Number of polycubes of size n and symmetry class BD.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 3, 1, 0, 1, 0, 0, 4, 2, 2, 3, 4, 0, 23, 7, 5, 10, 3, 1, 48, 16, 19, 28, 49, 2, 174, 49, 58, 84, 46, 18, 406, 111, 169, 238, 424, 34, 1285, 321, 524, 678, 410, 153, 3139, 747, 1393, 1872, 3185
Offset: 1

Views

Author

John Mason, Oct 17 2024

Keywords

Comments

See link "Counting free polycubes" for explanation of notation.

Crossrefs

A377129 Number of polycubes of size n and symmetry class CCC.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 2, 1, 0, 0, 3, 0, 2, 2, 2, 0, 1, 1, 9, 2, 0, 0, 14, 1, 7, 5, 10, 1, 4, 4, 31, 6, 6, 4, 42, 4, 25, 13, 45, 9, 15, 13, 111, 20, 28, 21, 143, 14, 95, 44, 175, 34, 64, 44, 401, 68, 111, 76, 482
Offset: 1

Views

Author

John Mason, Oct 17 2024

Keywords

Comments

See link "Counting free polycubes" for explanation of notation.

Crossrefs

A377130 Number of polycubes of size n and symmetry class DEE.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 3, 1, 0, 0, 0, 1, 6, 2, 1, 0, 0, 4, 13, 5, 1, 0, 0, 6, 28, 9, 4, 0, 0, 20, 61, 26, 7, 0, 0, 36, 129, 43, 18, 0, 0, 94, 274, 109, 33, 0, 0, 182, 582, 201, 81, 2, 0, 438, 1231, 501
Offset: 1

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Author

John Mason, Oct 17 2024

Keywords

Comments

See link "Counting free polycubes" for explanation of notation.

Crossrefs

A038172 Number of "connected animals" formed from n rhombic dodecahedra (or edge-connected cubes) in the face-centered cubic lattice, allowing translation and rotations of the lattice.

Original entry on oeis.org

1, 1, 5, 28, 225, 2274, 24955, 286143, 3367443, 40358811, 490598186
Offset: 1

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Author

Keywords

Crossrefs

Extensions

This extends earlier work of Torsten Sillke (TORSTEN.SILLKE(AT)LHSYSTEMS.COM). Added the 10th term.
a(11) from Joerg Arndt and Márk Péter Légrádi, Apr 30 2023

A038180 Number of "connected animals" formed from n square- or hexagon-connected truncated octahedra in the b.c.c. lattice, allowing translation and rotations of the lattice.

Original entry on oeis.org

1, 2, 6, 44, 394, 4680, 59361, 789303, 10742595, 148921162, 2093400002, 29769338104
Offset: 1

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Author

Torsten Sillke (TORSTEN.SILLKE(AT)LHSYSTEMS.COM)

Keywords

Crossrefs

Extensions

Corrected and extended by Achim Flammenkamp
Definition corrected by Fred Bayer, Aug 11 2010
More terms from Mark Owen, Oct 11 2013

A292157 Number of Besźel [Beszel] Polycubes with n cells, identifying mirror images. A Besźel Polycube is a polycube whose cells each have two or more even coordinates.

Original entry on oeis.org

1, 1, 2, 4, 11, 23, 80, 230, 837, 2935, 11251, 43364, 173205, 699160, 2868527, 11872515, 49583430, 208407805, 881085265
Offset: 1

Views

Author

George Sicherman, Sep 09 2017

Keywords

Comments

This sequence also gives the number of Ul Qoma Polycubes with n cells. An Ul Qoma Polycube is a polycube whose cells each have two or more odd coordinates.

Examples

			a(4) = 4 because 4 of the 8 tetracubes (I, L, T, K) can be embedded in the Besźel section of the cubic grid.
		

References

  • China Miéville, The City & the City, Macmillan, 2009.

Crossrefs

Cf. A292065: Number of Besźel Polycubes with n cells, distinguishing mirror images; A038119: Number of polycubes with n cells, identifying mirror images.

Extensions

a(11) - a(19) from Joerg Arndt, Dec 12 2023

A355966 Number of 3-dimensional polyominoes (or polycubes) with n cells that have cavities (inclusions of empty space).

Original entry on oeis.org

20, 404, 6164, 75917, 835491
Offset: 11

Views

Author

Gleb Ivanov, Jul 21 2022

Keywords

Comments

Even if two polycubes are mirror images of each other, they are considered different for this sequence.
Polycubes with less than 11 cells can't have cavities.
Largest enclosed volume >= A355880(n-5) for polycubes with n cells.

Crossrefs

Cf. A357083 (without distinguished reflections).
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