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 1-2 of 2 results.

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

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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

A294151 Number of perforated polyominoes with n cells, identifying mirror images.

Original entry on oeis.org

1, 1, 2, 3, 8, 13, 36, 76, 202, 482, 1281, 3277, 8749, 23083, 62056, 166498, 450576, 1220542, 3321870, 9057388, 24769906
Offset: 1

Views

Author

George Sicherman, Oct 23 2017

Keywords

Comments

A perforated polyomino is a polyomino in which every cell has at least one even coordinate.

Examples

			a(4)=3 because there are 5 tetrominoes, and the skew and square tetrominoes do not lie in the perforated grid, which leaves 3.
		

Crossrefs

Cf. A000105, number of polyominoes with n cells; A292065, number of Besźel Polycubes with n cells, distinguishing mirror images; A292157, same but identifying mirror images.

Extensions

a(16) - a(21) from Joerg Arndt, Dec 11 2023
Showing 1-2 of 2 results.