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.

Previous Showing 11-19 of 19 results.

A151835 Number of fixed 9-dimensional polycubes with n cells.

Original entry on oeis.org

1, 9, 153, 3309, 81837, 2205489, 63113061, 1887993993, 58441956579, 1858846428437, 60445700665383, 2001985304489169, 67341781440810531, 2295424989986481345
Offset: 1

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Author

N. J. A. Sloane, Jul 12 2009

Keywords

Comments

a(1)-a(10) can be computed by formulas in Barequet et al. (2010). Luther and Mertens confirm these values (and add two more) by direct counting.

Crossrefs

Extensions

a(5)-a(12) from Luther and Mertens by Gill Barequet, Jun 12 2011
a(13)-a(14) from Mertens added by Andrey Zabolotskiy, Jan 29 2023

A366335 Number of fixed (4,2)-polyominoids with n cells.

Original entry on oeis.org

6, 60, 916, 16698, 336210, 7218768, 162185112, 3769221330, 89924613880
Offset: 1

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Author

Pontus von Brömssen, Oct 07 2023

Keywords

Comments

A (D,d)-polyominoid is a connected set of d-dimensional unit cubes with integer coordinates in D-dimensional space, where two cubes are connected if they share a (d-1)-dimensional facet. For example, (3,2)-polyominoids are normal polyominoids (A075678), (D,D)-polyominoids are D-dimensional polyominoes (A001168, A001931, A151830, ...), and (D,1)-polyominoids are polysticks in D dimensions (A096267, A365560, A365562, ...).

Crossrefs

Cf. A366334 (free).
46th row of A366767.
Fixed (D,d)-polyominoids:
D\d| 1 2 3 4
---+--------------------------------
1 | A000012

Extensions

a(7)-a(9) from John Mason, Jul 05 2025

A007743 Number of achiral polyominoes with n cubical cells of the regular tiling with Schläfli symbol {4,3,4} (or polycubes).

Original entry on oeis.org

1, 1, 2, 6, 17, 58, 191, 700, 2515, 9623, 36552, 143761, 564443, 2259905, 9057278, 36705846, 149046429, 609246350, 2495727647, 10267016450, 42322763940, 174974139365
Offset: 1

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Author

Arlin Anderson (starship1(AT)gmail.com)

Keywords

Comments

A000162 but with both copies of each mirror-image deleted.
An achiral polyomino is identical to its reflection. Many of these achiral polyominoes do not have a plane of symmetry. For example, the hexomino with cell centers (0,0,0), (0,0,1), (0,1,1), (1,1,1), (1,2,1), and (1,2,2) has a center of symmetry at (1/2,1,1) but no plane of symmetry. The decomino with cell centers (0,0,0), (0,0,1), (0,1,1), (0,2,1), (0,2,2), (1,0,2), (1,1,2), (1,1,1), (1,1,0), and (1,2,0) has no plane or center of symmetry. - Robert A. Russell, Mar 21 2024

Crossrefs

Formula

a(n) = A000162(n) - 2*A371397(n) = A038119(n) - A371397(n). - Robert A. Russell, Mar 21 2024

Extensions

a(13)-a(16) from Herman Jamke (hermanjamke(AT)fastmail.fm), May 05 2007
Changed "symmetric" to "mirror-symmetric" in the title by George Sicherman, Feb 21 2018
Changed "mirror-symmetric" to "achiral" in the title to ensure that a plane of symmetry is not required. - Robert A. Russell, Mar 21 2024
a(17)-a(22) from John Mason, Sep 19 2024

A229914 Number of pyramid polycubes of a given volume in dimension 3.

Original entry on oeis.org

1, 3, 7, 16, 33, 63, 117, 202, 344, 566, 908, 1419, 2206, 3334, 4988, 7378, 10778, 15535, 22281, 31547, 44405, 62011, 85939, 118281, 162136, 220494, 298531, 402163, 539181, 719301, 956287, 1265022, 1667973, 2190934, 2867470, 3739797, 4864163, 6303461, 8146863, 10499087, 13493267, 17293169, 22111954
Offset: 1

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Author

Matthieu Deneufchâtel, Oct 03 2013

Keywords

Comments

A pyramid polycube is obtained by gluing together horizontal plateaux (parallelepipeds of height 1) in such a way that (0,0,0) belongs to the first plateau and each cell of coordinate (0,b,c) belonging to the first plateau is such that b , c >= 0.
If the cell with coordinates (a,b,c) belongs to the (a+1)-st plateau (a>0), then the cell with coordinates (a-1, b, c) belongs to the a-th plateau.

Crossrefs

A001931 is an upper bound.

Formula

The generating function for the numbers of pyramids of height h and volumes v_1 , ... v_h is (n_1-n_2+1) *(n_2-n_3+1) *... *(n_{h-1}-n_h+1) *(x_1^{n_1} * ... x_h^{n_h}) / ((1-x_1^{n_1}) *(1-x_1^{n_1}*x_2^{n_2}) *... *(1-x_1^{n_1}*x_2^{n_2}*...x_h^{n_h})).
This sequence is obtained with x_1 = ... = x_h = p by summing over n_1>=, ... >= n_h>=1 and then over h.

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

A385291 Square array read by descending antidiagonals: A(n,k) is the number of fixed n-dimensional polyominoes of size k.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 1, 6, 3, 1, 1, 19, 15, 4, 1, 1, 63, 86, 28, 5, 1, 1, 216, 534, 234, 45, 6, 1, 1, 760, 3481, 2162, 495, 66, 7, 1, 1, 2725, 23502, 21272, 6095, 901, 91, 8, 1, 1, 9910, 162913, 218740, 80617, 13881, 1484, 120, 9, 1, 1, 36446, 1152870, 2323730, 1121075, 231008, 27468, 2276, 153, 10, 1
Offset: 1

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Author

John Mason, Jun 24 2025

Keywords

Examples

			The top corner of the array (size on horizontal axis, dimensions on vertical):
          1: 1  1    1     1       1         1           1
(A001168) 2: 1  2    6    19      63       216         760
(A001931) 3: 1  3   15    86     534      3481       23502
(A151830) 4: 1  4   28   234    2162     21272      218740
(A151831) 5: 1  5   45   495    6095     80617     1121075
(A151832) 6: 1  6   66   901   13881    231008     4057660
(A151833) 7: 1  7   91  1484   27468    551313    11710328
(A151834) 8: 1  8  120  2276   49204   1156688    28831384
(A151835) 9: 1  9  153  3309   81837   2205489    63113061
         10: 1 10  190  4615  128515   3906184   126210640
         11: 1 11  231  6226  192786   6524265   234919234
         12: 1 12  276  8174  278598  10389160   412504236
         13: 1 13  325 10491  390299  15901145   690185431
         14: 1 14  378 13209  532637  23538256  1108774772
         15: 1 15  435 16360  710760  33863201  1720467820
         16: 1 16  496 19976  930216  47530272  2590788848
         17: 1 17  561 24089 1196953  65292257  3800689609
         18: 1 18  630 28731 1517319  88007352  5448801768
         19: 1 19  703 33934 1898062 116646073  7653842998
         20: 1 20  780 39730 2346330 152298168 10557176740
         21: 1 21  861 46151 2869671 196179529 14325525627
         22: 1 22  946 53229 3476033 249639104 19153838572
         23: 1 23 1035 60996 4173764 314165809 25268311520
         24: 1 24 1128 69484 4971612 391395440 32929561864
		

Crossrefs

Cf. A000384 (column k=3), A195739.
Rows: A000012 (n=1), A001168 (n=2), A001931 (n=3), A151830 (n=4), A151831 (n=5), A151832 (n=6), A151833 (n=7), A151834 (n=8), A151835 (n=9).

Formula

A(n,k) = Sum_{d=0..n} binomial(n,d)*A195739(k,d) (with A195739(k,d) = 0 for k <= d). - Pontus von Brömssen, Jun 28 2025

Extensions

a(56)-a(66) from Pontus von Brömssen, Jun 28 2025

A006763 Number of fixed properly-3-dimensional polyominoes with n cells.

Original entry on oeis.org

0, 0, 0, 32, 348, 2836, 21225, 154741, 1123143, 8185403, 60088748, 444688325, 3317057654, 24925158492, 188543716451, 1434760675947, 10976610064899, 84379534826376, 651441493579872
Offset: 1

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Author

Keywords

References

  • N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence).

Crossrefs

A column of A195739.

Programs

Formula

a(n) = A001931(n) - 3 * (A001168(n) - 1) for n > 1. - Sean A. Irvine, Jul 27 2017

Extensions

More terms from Jean-François Alcover, Sep 22 2019

A113174 Number of fixed 3D piled polyominoes: polycubes with fixed orientation, with no cubes "sitting on air".

Original entry on oeis.org

1, 3, 11, 44, 184, 792, 3484, 15592, 70745, 324561, 1502511, 7007929, 32892778, 155221536, 735915652, 3503270920, 16737092549, 80218277681, 385574074383, 1858059853316, 8974761939239, 43441619693731, 210682920968681
Offset: 1

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Author

Keywords

Examples

			For n = 4, there are 4 orientations of the angled tricube excluded: those which set it on a point; this leaves 8 orientations of the angled tricube and 3 of the straight tricube.
		

Crossrefs

Cf. A001168, A001931 (fixed polycubes).

Formula

a(n) = sum_{m=1}^n A001168(m)*C(n-1, m-1). If both sequences are shifted left, binomial transform of A001168.

Extensions

Corrected by Franklin T. Adams-Watters, Oct 25 2006

A363090 Number of 3-dimensional directed animals of size n.

Original entry on oeis.org

1, 3, 12, 52, 237, 1113, 5339, 26011, 128247, 638346, 3201967, 16164384, 82044151, 418352107, 2141761669, 11003117220
Offset: 1

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Author

Keywords

Comments

Fixed 3-dimensional fixed polycubes with neighborhood vectors [1, 0, 0], [0, 1, 0], and [0, 0, 1].
A005773 is the 2-dimensional equivalent: fixed polyominoes with neighborhood vectors [1, 0] and [0, 1].
Using neighborhood vectors [+-1, 0, 0], [0, +-1, 0], and [0, 0, +-1] gives A001931.

Crossrefs

Cf. A005773.

Extensions

a(14)-a(16) from Johann Peters, Nov 21 2024
Previous Showing 11-19 of 19 results.