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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A376971 Number of polycubes of size n and symmetry class G (full symmetry).

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 2, 1, 0, 0, 0, 1, 2, 1, 1, 0, 0, 1, 2, 3, 1, 0, 0, 1, 3, 1, 1, 0, 0, 4, 5, 4, 1, 0, 0, 6, 7, 4, 3, 0, 0, 8, 10, 11, 3, 0, 0, 12, 14, 8, 5, 1, 0, 22, 21, 21, 7, 0, 0, 34, 32, 20, 12, 2, 0, 50, 48, 48, 16, 1, 1, 76, 69, 48, 27, 8, 1
Offset: 1

Views

Author

John Mason, Oct 11 2024

Keywords

Comments

See link "Counting free polycubes" for explanation of notation.
a(n) = 0 if and only if n is in the set {2, 3, 4, 5, 6, 9, 10, 11, 12, 14, 15, 16, 17, 21, 22, 23, 28, 29, 34, 35, 40, 41, 46, 47, 52, 53, 58, 59, 65, 70, 71, 77}. (See link "Polycubes with full symmetry".) - Pontus von Brömssen, Oct 12 2024
Conjecture: For n >= 62, a(n) > a(n-1) if and only if n is a multiple of 6. - Pontus von Brömssen, Oct 20 2024

Crossrefs

Cf. A000162, A038119, A142886 (polyominoes with full symmetry), A066288 (symmetric with rotations, group order 24).

Extensions

a(32)-a(36) from Pontus von Brömssen, Oct 14 2024
More terms from Pontus von Brömssen, Oct 20 2024

A002880 Number of 3-connected nets with n edges.

Original entry on oeis.org

1, 0, 1, 1, 2, 2, 9, 11, 37, 79, 249, 671, 2182, 6692, 22131, 72405, 243806, 822788, 2815119, 9679205, 33551192, 116900081, 409675567, 1442454215, 5102542680, 18124571838, 64634480340, 231334873091, 830828150081, 2993489821771
Offset: 6

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Keywords

Comments

Also, the number of 3-connected quadrangulations without separating 4-cycles (up to orientation) with n faces. - Andrey Zabolotskiy, Sep 20 2019

Examples

			G.f. = x^6 + x^8 + x^9 + 2*x^10 + 2*x^11 + 9*x^12 + 11*x^13 + 37*x^14 + ...
		

References

  • 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

A268666 Number of polycubes with n cells, allowing edge connections as well as face connections, identifying mirror images.

Original entry on oeis.org

1, 2, 8, 64, 646, 9364, 151028, 2605148, 46350675
Offset: 1

Views

Author

George Sicherman, Feb 10 2016

Keywords

Examples

			a(2) = 2 because there are two ways to join two cells in the cubic grid at faces or edges.
		

Crossrefs

Cf. A270862 (distinguishing mirror images), A038119, A000162, A030222 (2-dimensional polyplets).
34th row of A366766.

Extensions

a(8)-a(9) from John Mason, Aug 04 2021

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

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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

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

Views

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

A038170 Number of "connected animals" formed from n 6-gon connected truncated octahedra (or corner-connected cubes) in the b.c.c. lattice, allowing translation and rotations of the lattice.

Original entry on oeis.org

1, 1, 3, 14, 88, 686, 5966, 54722, 516454, 4970445, 48527372, 479314799
Offset: 1

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Keywords

Crossrefs

Extensions

a(11) and a(12) from Joerg Arndt and Márk Péter Légrádi, May 02 2023

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

Views

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

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

Views

Author

John Mason, Oct 17 2024

Keywords

Comments

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

Crossrefs

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