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 1-8 of 8 results.

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

A365366 Number of free 4-dimensional polyhypercubes with n cells, allowing corner-, edge-, face-, and 3-face-connections.

Original entry on oeis.org

1, 4, 30, 835, 43828
Offset: 1

Views

Author

Pontus von Brömssen, Sep 05 2023

Keywords

Crossrefs

Connections |
(0 = corner, 1 = edge, | Polyhypercubes in dimension
2 = face, 3 = 3-face) | 2 3 4
-----------------------+----------------------------
3 | A068870
0 3 | A365360
1 3 | A365361
01 3 | A365362
23 | A365363
0 23 | A365364
123 | A365365
0123 | A365366
*There is a one-to-one correspondence between corner-connected and edge-connected 2-dimensional polyominoes, but see A364928.
154th row of A366766.

A038174 Number of "polyspheres", or "connected animals" formed from n rhombic dodecahedra (or edge-connected cubes) in the f.c.c. lattice, allowing translation and rotations of the lattice, reflections and 180 deg. rotations about a 3-fold symmetry axis of the lattice.

Original entry on oeis.org

1, 1, 4, 25, 210, 2209, 24651, 284768, 3360995, 40328652, 490455189
Offset: 1

Views

Author

Achim Flammenkamp, Torsten Sillke (TORSTEN.SILLKE(AT)LHSYSTEMS.COM)

Keywords

Crossrefs

Extensions

a(9) and a(10) from Achim Flammenkamp Feb 15 1999
a(11) from Ishino Keiichiro's website added by Andrey Zabolotskiy, Mar 03 2023

A038169 Number of "connected animals" formed from n triakis truncated tetrahedra connected along hexagonal faces in the triakis truncated tetrahedral honeycomb, allowing translations, rotations, and reflections of the honeycomb.

Original entry on oeis.org

1, 1, 1, 3, 7, 24, 88, 385, 1713, 8112, 38869, 190128, 938357
Offset: 1

Views

Author

Keywords

Comments

Previous name was 'Number of "connected animals" formed from n tricapped truncated tetrahedra in the diamond lattice, allowing translation and rotations of the lattice and reflections.' - Peter Kagey, May 30 2025

References

  • A. T. Balaban and Paul von R. Schleyer, "Graph theoretical enumeration of polymantanes", Tetrahedron, (1978), vol. 34, pp. 3599-3609. See Page 3605.

Crossrefs

Extensions

Name changed by Peter Kagey, May 30 2025

A384755 Triangle read by rows: T(n,k) is the number of face-connected components of polyhedra with k prisms and n-k truncated cuboctahedra in the omnitruncated cubic honeycomb up to rotation and reflection, 0 <= k <= n.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 3, 7, 10, 2, 12, 41, 76, 46, 4, 61, 335, 809, 777, 232, 13, 407, 3065, 9512, 12863, 7186, 1206, 39, 3226, 30401, 114516, 204143, 172377, 60421, 6548, 155, 28335, 311782, 1381363, 3054599, 3507278, 1975767, 469525, 36081, 637, 262091, 3260971, 16569719, 43731912
Offset: 0

Views

Author

Peter Kagey, Jun 09 2025

Keywords

Comments

Row sums are A384754.

Examples

			0 |   1;
1 |   1,    1;
2 |   1,    2,    1;
3 |   3,    7,   10,     2;
4 |  12,   41,   76,    46,    4;
5 |  61,  335,  809,   777,  232,   13;
6 | 407, 3065, 9512, 12863, 7186, 1206, 39;
		

Crossrefs

Cf. A365970 (tetrahedral-octahedral honeycomb), A384486 (quarter cubic honeycomb), A384782 (rectified cubic honeycomb).

Formula

T(n,0) = A038171(n).

Extensions

More terms from Bert Dobbelaere, Jun 14 2025

A365353 Number of free corner-connected 4-dimensional polyhypercubes with n cells.

Original entry on oeis.org

1, 1, 4, 23, 207, 2794
Offset: 1

Views

Author

Pontus von Brömssen, Sep 02 2023

Keywords

Crossrefs

147th row of A366766.
See A365366 for a table of similar sequences.

A039741 Number of fixed n-celled lattice animals in the b.c.c. lattice (8 nearest neighbors), or connected truncated octahedra, or vertex-connected cubes.

Original entry on oeis.org

1, 4, 28, 216, 1790, 15587, 140746, 1305920, 12374069, 119223556, 1164465225, 11502924648, 114721053058, 1153539900783
Offset: 1

Views

Author

Keywords

Crossrefs

Cf. A038171 (free).
35th row of A366767.

A363200 Number of connected animals formed from n 6-gon connected truncated octahedra, avoiding connected squares.

Original entry on oeis.org

1, 1, 2, 5, 15, 55, 248, 1256, 6844, 38930, 226961, 1345641, 8072770, 48882245, 298237393
Offset: 1

Views

Author

Keywords

Comments

Rotations and reflections are identified.
Avoiding connected squares is the same as avoiding neighbors at [0,0,+-2], [0,+-2,0], and [+-2,0,0].
Allowing connected squares gives A038171.

Examples

			The animals for n <= 5 are:
n=1:
  0,0,0
n=2:
  0,0,0; 1,1,1
n=3:
  0,0,0; 0,2,2; 1,1,1
  0,0,0; 1,1,1; 2,2,2
n=4:
  0,0,0; 0,2,2; 1,1,1; 1,3,3
  0,0,0; 0,2,2; 1,1,1; 2,0,2
  0,0,0; 1,1,1; 1,3,3; 2,2,2
  0,0,0; 1,1,1; 2,2,2; 3,3,3
  0,0,1; 1,1,0; 1,3,2; 2,2,1
n=5:
  0,0,0; 0,2,2; 0,4,4; 1,1,1; 1,3,3
  0,0,0; 0,2,2; 1,1,1; 1,3,3; 2,0,2
  0,0,0; 0,2,2; 1,1,1; 1,3,3; 2,2,4
  0,0,0; 0,2,2; 1,1,1; 1,3,3; 2,4,4
  0,0,0; 0,2,2; 1,1,1; 2,0,2; 2,2,0
  0,0,0; 0,2,4; 1,1,1; 1,3,3; 2,2,2
  0,0,0; 0,4,4; 1,1,1; 1,3,3; 2,2,2
  0,0,0; 1,1,1; 1,3,3; 2,2,2; 3,1,3
  0,0,0; 1,1,1; 2,2,2; 2,4,4; 3,3,3
  0,0,0; 1,1,1; 2,2,2; 3,3,3; 4,4,4
  0,0,1; 0,2,3; 1,1,0; 1,3,2; 2,2,1
  0,0,1; 0,2,3; 1,1,2; 1,3,0; 2,2,1
  0,0,1; 0,4,1; 1,1,0; 1,3,2; 2,2,1
  0,0,1; 1,1,0; 2,2,1; 2,4,3; 3,3,2
  0,0,1; 1,1,0; 2,2,1; 3,3,2; 4,4,1
		

Extensions

a(14) and a(15) from Joerg Arndt, Dec 09 2023
Showing 1-8 of 8 results.