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 1-10 of 88 results. Next

A006986 Erroneous version of A038119.

Original entry on oeis.org

1, 1, 2, 7, 23, 114, 625, 3974
Offset: 1

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A112089 Erroneous version of A038119.

Original entry on oeis.org

1, 1, 1, 2, 7, 24
Offset: 0

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A000162 Number of 3-dimensional polyominoes (or polycubes) with n cells.

Original entry on oeis.org

1, 1, 2, 8, 29, 166, 1023, 6922, 48311, 346543, 2522522, 18598427, 138462649, 1039496297, 7859514470, 59795121480, 457409613979, 3516009200564, 27144143923583, 210375361379518, 1636229771639924, 12766882202755783
Offset: 1

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Keywords

Comments

Here two polycubes that differ by reflection are considered different. - Joerg Arndt, Apr 26 2023
Number of oriented polyominoes with n cubical cells of the regular tiling with Schläfli symbol {4,3,4}. For oriented polyominoes, chiral pairs are counted as two. - Robert A. Russell, Mar 21 2024

Examples

			Table showing total number and numbers with each group order.
-------------------------------------------------------------
The last 7 columns form sequences A066453, A066454, A066273, A066281, A066283, A066287, A066288.
.n ...A000162 ..group:.1.....2...3...4.6.8.24
.1 .........1..........0.....0...0...0.0.0..1
.2 .........1..........0.....0...0...0.0.1..0
.3 .........2..........0.....1...0...0.0.1..0
.4 .........8..........1.....4...1...0.0.2..0
.5 ........29.........17....10...0...0.0.2..0
.6 .......166........127....34...0...3.1.1..0
.7 ......1023........941....71...4...5.0.1..1
.8 ......6922.......6662...246...0..11.0.2..1
.9 .....48311......47771...522...3..11.0.4..0
10 ....346543.....344708..1783..24..24.2.2..0
11 ...2522522....2518713..3765...4..35.0.5..0
12 ..18598427...18585455.12858..18..84.5.7..0
13 .138462649..138434899.27496.151..92.2.8..1
14 1039496297.1039401564.94525..25.174.4.5..0
		

References

  • C. J. Bouwkamp, personal communication.
  • W. F. Lunnon, Symmetry of cubical and general polyominoes, pp. 101-108 of R. C. Read, editor, Graph Theory and Computing. Academic Press, NY, 1972.
  • W. F. Lunnon, personal communication.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Cf. A038119 (unoriented), A371397 (chiral), A007743 (achiral), A001931 (fixed).

Formula

a(n) = 2*A038119 - A007743.
a(n) = A000105 + A006759.
a(n) = A038119(n) + A371397(n) = 2*A371397(n) + A007743(n). - Robert A. Russell, Mar 21 2024

Extensions

The old value for a(11), 2522572, was corrected by Achim Flammenkamp to 2522522, Feb 15 1999.
a(13)-a(14) from Brendan Owen (brendan_owen(AT)yahoo.com), Dec 27 2001
a(15)-a(16) from Herman Jamke (hermanjamke(AT)fastmail.fm), May 05 2007
a(17)-a(20) from Stanley Dodds, Dec 11 2023
a(21)-a(22) (using Dodds's algorithm) from Phillip Thompson, Feb 07 2024

A366766 Array read by antidiagonals, where each row is the counting sequence of a certain type of free polyominoids (see comments).

Original entry on oeis.org

1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 0, 1, 3, 2, 1, 0, 1, 0, 1, 7, 5, 0, 1, 0, 1, 0, 1, 20, 16, 0, 1, 1, 0, 1, 0, 1, 60, 55, 0, 2, 1, 1, 0, 1, 0, 1, 204, 222, 0, 5, 2, 2, 1, 0, 1, 0, 1, 702, 950, 0, 12, 5, 5, 0, 1
Offset: 1

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Author

Pontus von Brömssen, Oct 22 2023

Keywords

Comments

A (D,d)-polyominoid is a connected set of d-dimensional unit cubes (cells) with integer coordinates in D-dimensional space. For normal polyominoids, two cells are connected if they share a (d-1)-dimensional facet, but here we allow connections where the cells share a lower-dimensional face.
Each row is the counting sequence (by number of cells) of (D,d)-polyominoids with certain restrictions on the allowed connections between cells. Two cells have a connection of type (g,h) if they intersect in a (d-g)-dimensional unit cube and extend in d-h common dimensions. For example, d-dimensional polyominoes use connections of type (1,0), polyplets use connections of types (1,0) (edge connections) and (2,0) (corner connections), normal (3,2)-polyominoids use connections of types (1,0) ("soft" connections) and (1,1) ("hard" connections), hard polyominoids use connections of type (1,1).
Each row corresponds to a triple (D,d,C), where 1 <= d <= D and C is a set of pairs (g,h) with 1 <= g <= d and 0 <= h <= min(g, D-d). The k-th term of that row is the number of free k-celled (D,d)-polyominoids with connections of the types in C. Connections of types not in C are permitted, but the polyominoids must be connected through the specified connections only. For example, polyominoes may have cells that intersect in a point (g = 2) and hard polyominoids can have soft connections (h = 0) that are not needed to keep the polyominoids connected.
The rows are sorted first by D, then by d, and finally by a binary vector indicating which types of connections are allowed, where the connection types (g,h) are sorted lexicographically. (See table in cross-references.)
For each pair (D,d), the first row is 1, 0, 0, ..., corresponding to (D,d,{}) (no connections allowed).
The number of rows corresponding to given values of D and d is 2^((d+1)*(d+2)/2-1) if 2*d <= D and 2^((D-d+1)*(3*d-D+2)/2-1) otherwise.

Examples

			Array begins:
  n\k| 1  2  3  4  5   6    7     8      9     10      11       12
  ---+------------------------------------------------------------
   1 | 1  0  0  0  0   0    0     0      0      0       0        0
   2 | 1  1  1  1  1   1    1     1      1      1       1        1
   3 | 1  0  0  0  0   0    0     0      0      0       0        0
   4 | 1  1  1  1  1   1    1     1      1      1       1        1
   5 | 1  1  3  7 20  60  204   702   2526   9180   33989   126713
   6 | 1  2  5 16 55 222  950  4265  19591  91678  434005  2073783
   7 | 1  0  0  0  0   0    0     0      0      0       0        0
   8 | 1  1  2  5 12  35  108   369   1285   4655   17073    63600
   9 | 1  1  2  5 12  35  108   369   1285   4655   17073    63600
  10 | 1  2  5 22 94 524 3031 18770 118133 758381 4915652 32149296
  11 | 1  0  0  0  0   0    0     0      0      0       0        0
  12 | 1  1  1  1  1   1    1     1      1      1       1        1
		

Crossrefs

Cf. A366767 (fixed), A366768.
The following table lists some sequences that are rows of the array, together with the corresponding values of D, d, and C. Some sequences occur in more than one row. Notation used in the table:
X: Allowed connection.
-: Not allowed connection (but may occur "by accident" as long as it is not needed for connectedness).
.: Not applicable for (D,d) in this row.
!: d < D and all connections have h = 0, so these polyominoids live in d < D dimensions only.
*: Whether a connection of type (g,h) is allowed or not is independent of h.
| | | connections |
| | | g:1122233334 |
n | D | d | h:0101201230 | sequence
----+---+---+--------------+---------
1 | 1 | 1 | * -......... | A063524
2 | 1 | 1 | * X......... | A000012
3 |!2 | 1 | * --........ | A063524
4 |!2 | 1 | X-........ | A000012
5 | 2 | 1 | -X........ | A361625
6 | 2 | 1 | * XX........ | A019988
7 | 2 | 2 | * -.-....... | A063524
8 | 2 | 2 | * X.-....... | A000105
9 | 2 | 2 | * -.X....... | A000105
10 | 2 | 2 | * X.X....... | A030222
11 |!3 | 1 | * --........ | A063524
12 |!3 | 1 | X-........ | A000012
13 | 3 | 1 | -X........ | A365654
14 | 3 | 1 | * XX........ | A365559
15 |!3 | 2 | * ----...... | A063524
16 |!3 | 2 | X---...... | A000105
17 | 3 | 2 | -X--...... | A365654
18 | 3 | 2 | * XX--...... | A075679
19 |!3 | 2 | --X-...... | A000105
20 |!3 | 2 | X-X-...... | A030222
21 | 3 | 2 | -XX-...... | A365995
22 | 3 | 2 | XXX-...... | A365997
23 | 3 | 2 | ---X...... | A365999
24 | 3 | 2 | X--X...... | A366001
25 | 3 | 2 | -X-X...... | A366003
26 | 3 | 2 | XX-X...... | A366005
27 | 3 | 2 | * --XX...... | A365652
28 | 3 | 2 | X-XX...... | A366007
29 | 3 | 2 | -XXX...... | A366009
30 | 3 | 2 | * XXXX...... | A365650
31 | 3 | 3 | * -.-..-.... | A063524
32 | 3 | 3 | * X.-..-.... | A038119
33 | 3 | 3 | * -.X..-.... | A038173
34 | 3 | 3 | * X.X..-.... | A268666
35 | 3 | 3 | * -.-..X.... | A038171
36 | 3 | 3 | * X.-..X.... | A363205
37 | 3 | 3 | * -.X..X.... | A363206
38 | 3 | 3 | * X.X..X.... | A272368
39 |!4 | 1 | * --........ | A063524
40 |!4 | 1 | X-........ | A000012
41 | 4 | 1 | -X........ | A366340
42 | 4 | 1 | * XX........ | A365561
43 |!4 | 2 | * -----..... | A063524
44 |!4 | 2 | X----..... | A000105
45 | 4 | 2 | -X---..... | A366338
46 | 4 | 2 | * XX---..... | A366334
47 |!4 | 2 | --X--..... | A000105
48 |!4 | 2 | X-X--..... | A030222
...
75 |!4 | 3 | * ----.--... | A063524
76 |!4 | 3 | X---.--... | A038119
77 | 4 | 3 | -X--.--... | A366340
78 | 4 | 3 | * XX--.--... | A366336
...
139 | 4 | 4 | * -.-..-...- | A063524
140 | 4 | 4 | * X.-..-...- | A068870
141 | 4 | 4 | * -.X..-...- | A365356
142 | 4 | 4 | * X.X..-...- | A365363
143 | 4 | 4 | * -.-..X...- | A365354
144 | 4 | 4 | * X.-..X...- | A365361
145 | 4 | 4 | * -.X..X...- | A365358
146 | 4 | 4 | * X.X..X...- | A365365
147 | 4 | 4 | * -.-..-...X | A365353
148 | 4 | 4 | * X.-..-...X | A365360
149 | 4 | 4 | * -.X..-...X | A365357
150 | 4 | 4 | * X.X..-...X | A365364
151 | 4 | 4 | * -.-..X...X | A365355
152 | 4 | 4 | * X.-..X...X | A365362
153 | 4 | 4 | * -.X..X...X | A365359
154 | 4 | 4 | * X.X..X...X | A365366
155 |!5 | 1 | * --........ | A063524
156 |!5 | 1 | X-........ | A000012
157 | 5 | 1 | -X........ |
158 | 5 | 1 | * XX........ | A365563

A038173 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 and reflections.

Original entry on oeis.org

1, 1, 4, 20, 131, 1211, 12734, 144158, 1687737, 20196788, 245366931, 3016835487
Offset: 1

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Keywords

Comments

This extends earlier work of Torsten Sillke (torsten.sillke(AT)lhsystems.com).

Crossrefs

Cf. A000162, A038119 (for simple-cubic lattice), A038168-A038174, A300812 (refined by number of contacts).
33rd row of A366766.

Extensions

a(10) from George Sicherman, Jul 24 2012
a(11) from Joerg Arndt and Márk Péter Légrádi, Apr 30 2023
a(12) from Bert Dobbelaere, Jun 26 2025

A343909 Number of generalized polyforms on the tetrahedral-octahedral honeycomb with n cells.

Original entry on oeis.org

1, 2, 1, 4, 9, 44, 195, 1186, 7385, 49444, 337504, 2353664, 16608401, 118432965, 851396696, 6163949361, 44896941979
Offset: 0

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Author

Drake Thomas and Peter Kagey, May 03 2021

Keywords

Comments

This sequence counts "free" polyforms where holes are allowed. This means that two polyforms are considered the same if one is a rigid transformation (translation, rotation, reflection, or a combination thereof) of the other.

Examples

			For n = 1, the a(1) = 2 polyforms are the tetrahedron and the octahedron.
For n = 2, the a(2) = 1 polyform is a tetrahedron and an octahedron connected at a face.
For n = 3, there are a(3) = 4 polyforms with 3 cells:
  - 3 consisting of one octahedron with two tetrahedra, and
  - 1 consisting of two octahedra and one tetrahedron.
For n = 4, there are a(4) = 9 polyforms with 4 cells:
  - 3 with one octahedron and three tetrahedra,
  - 5 with two octahedra and three octahedra, and
  - 1 with three octahedra and one tetrahedron.
For n = 5, there are a(5) = 44 polyforms with 5 cells:
  - 6 with one octahedron and four tetrahedra,
  - 24 with two octahedra and three tetrahedra,
  - 13 with three octahedra and two tetrahedra, and
  - 1 with four octahedra and one tetrahedron.
		

Crossrefs

Row sums of A365970.
Analogous for other honeycombs/tilings: A000105 (square), A000228 (hexagonal), A000577 (triangular), A038119 (cubical), A068870 (tesseractic), A197156 (prismatic pentagonal), A197159 (floret pentagonal), A197459 (rhombille), A197462 (kisrhombille), A197465 (tetrakis square), A309159 (snub square), A343398 (trihexagonal), A343406 (truncated hexagonal), A343577 (truncated square).

Extensions

a(11)-a(16) from Bert Dobbelaere, Jun 10 2025

A038181 Number of "connected animals" formed from n 4-gon or 6-gon connected truncated octahedra in the b.c.c. lattice, allowing translation and rotations of the lattice and reflections.

Original entry on oeis.org

1, 2, 6, 35, 251, 2602, 30900, 400818, 5401599, 74617105, 1047497078, 14888851869
Offset: 1

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Author

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

Keywords

Comments

These are "free polyforms" consisting of face-connected polyhedral cells in the bitruncated cubic honeycomb. - Peter Kagey, Jun 23 2025

Crossrefs

Extensions

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

A384254 Number of connected components of n polyhedra in the rectified cubic honeycomb up to translation, rotation, and reflection of the honeycomb.

Original entry on oeis.org

1, 2, 2, 9, 40, 290, 2529, 26629, 301289, 3568048, 43305326, 534671742, 6684869463
Offset: 0

Views

Author

Peter Kagey, May 23 2025

Keywords

Comments

Equivalently the number of connected components of n polyhedra in the truncated cubic honeycomb up to translation, rotation, and reflection of the honeycomb.

Examples

			For n=1, the a(1)=2 different components are the cuboctahedron and the octahedron.
For n=2, the a(2)=1 component is a cuboctahedron connected to an octahedron.
For n=3, there are A000162(3)=2 components that consist of three cuboctahedra, four connected components that consist of two cuboctahedra and an octahedron, and three components that consist of a cuboctahedron and two octahedra.
		

Crossrefs

Cf. A038119 (cubic honeycomb), A038181 (bitruncated cubic honeycomb), A343577 (truncated square tiling), A343909 (tetrahedral-octahedral honeycomb), A384274 (rectified cubic honeycomb).

Extensions

a(8)-a(12) from Bert Dobbelaere, Jun 09 2025

A384274 Number of connected components of polyhedra in the quarter cubic honeycomb up to translation, rotation, and reflection of the honeycomb.

Original entry on oeis.org

1, 2, 2, 5, 20, 96, 581, 4079, 31079, 247169, 2018826, 16771564, 141113504, 1199154541, 10274686867
Offset: 0

Views

Author

Peter Kagey, May 24 2025

Keywords

Crossrefs

Cf. A038119 (cubic honeycomb), A038181 (bitruncated cubic honeycomb), A343909 (tetrahedral-octahedral honeycomb), A384254 (rectified cubic honeycomb).
Cf. A384486.

Extensions

a(9)-a(14) from Bert Dobbelaere, Jun 12 2025

A001931 Number of fixed 3-dimensional polycubes with n cells; lattice animals in the simple cubic lattice (6 nearest neighbors), face-connected cubes.

Original entry on oeis.org

1, 3, 15, 86, 534, 3481, 23502, 162913, 1152870, 8294738, 60494549, 446205905, 3322769321, 24946773111, 188625900446, 1435074454755, 10977812452428, 84384157287999, 651459315795897, 5049008190434659, 39269513463794006, 306405169166373418
Offset: 1

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Author

Keywords

Comments

This gives the number of polycubes up to translation (but not rotation or reflection). - Charles R Greathouse IV, Oct 08 2013

References

  • W. F. Lunnon, Symmetry of cubical and general polyominoes, pp. 101-108 of R. C. Read, editor, Graph Theory and Computing. Academic Press, NY, 1972.
  • N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence).
  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

Extensions

Edited by Arun Giridhar, Feb 14 2011
a(17) from Achim Flammenkamp, Feb 15 1999
a(18) from the Aleksandrowicz and Barequet paper (N. J. A. Sloane, Jul 09 2009)
a(19) from Luther and Mertens by Gill Barequet, Jun 12 2011
a(20) from Stanley Dodds, Aug 03 2023
a(21)-a(22) (using Dodds's algorithm) from Phillip Thompson, Feb 07 2024
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