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 1-3 of 3 results.

A182644 Number of fixed snake polyominoes with n cells.

Original entry on oeis.org

1, 2, 6, 14, 34, 82, 198, 470, 1122, 2662, 6334, 14970, 35506, 83734, 198086, 466314, 1100818, 2587634, 6097830, 14316402, 33687146, 79008870, 185677006, 435098774, 1021404998, 2391646494, 5609151738, 13125214770, 30757286802, 71928506630
Offset: 1

Views

Author

Joseph Myers, Nov 24 2010

Keywords

Comments

This sequence counts snake polyominoes both with and without holes; for example, it counts all four of these 7-cell snakes:
### ## ## ###
# # # # # # # #
## ### ### ##

Links

Crossrefs

Snake polyominoes by group of symmetries relating shapes considered the same: A002013 (all symmetries), A182644 (translations only), A151514 (rotations and translations), A151527 (horizontal and vertical reflections, rotations of order 2 and translations), A151524 (reflections in either diagonal, rotations of order 2 and translations), A151523 (rotations of order 2 and translations), A151526 (reflections in a horizontal line and translations), A182646 (reflections in a NE-SW diagonal line and translations).

Extensions

More terms from Alain Goupil and Jérôme de Wouters, Jun 21 2014

A151526 Number of strip poly-IH64-tiles (holes allowed) with n cells.

Original entry on oeis.org

1, 2, 4, 8, 19, 43, 103, 239, 569, 1339, 3185, 7503, 17794, 41908, 99137, 233251, 550624, 1294032, 3049412, 7158698, 16844717, 39505579, 92841149
Offset: 1

Views

Author

Ed Pegg Jr, May 13 2009

Keywords

Comments

Equivalently, strip polyominoes where two polyominoes are considered the same if and only if they are related by a translation or a reflection in a horizontal line. Formerly described as one-sided strip polyrects, but that is A151523.

References

  • Branko Grünbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987, Sections 6.2 and 9.4.

Crossrefs

Strip polyominoes by group of symmetries relating shapes considered the same: A002013 (all symmetries), A182644 (translations only), A151514 (rotations and translations), A151527 (horizontal and vertical reflections, rotations of order 2 and translations), A151524 (reflections in either diagonal, rotations of order 2 and translations), A151523 (rotations of order 2 and translations), A151526 (reflections in a horizontal line and translations), A182646 (reflections in a NE-SW diagonal line and translations)

Extensions

Edited and a(15)-a(23) by Joseph Myers, Nov 24 2010

A182646 Number of strip poly-IH68-tiles (holes allowed) with n cells.

Original entry on oeis.org

1, 1, 4, 7, 19, 41, 104, 235, 572, 1331, 3193, 7485, 17811, 41867, 99181, 233157, 550718, 1293817, 3049649, 7158201, 16845217, 39504435, 92842398
Offset: 1

Views

Author

Joseph Myers, Nov 24 2010

Keywords

Comments

Equivalently, strip polyominoes where two polyominoes are considered the same if and only if they are related by a translation or a reflection in a NE-SW diagonal line.

References

  • Branko Grünbaum and G. C. Shephard, Tilings and Patterns. W. H. Freeman, New York, 1987, Sections 6.2 and 9.4.

Crossrefs

Strip polyominoes by group of symmetries relating shapes considered the same: A002013 (all symmetries), A182644 (translations only), A151514 (rotations and translations), A151527 (horizontal and vertical reflections, rotations of order 2 and translations), A151524 (reflections in either diagonal, rotations of order 2 and translations), A151523 (rotations of order 2 and translations), A151526 (reflections in a horizontal line and translations), A182646 (reflections in a NE-SW diagonal line and translations)
Showing 1-3 of 3 results.

Started in 1964 by Neil J. A. Sloane | Maintained by The OEIS Foundation Inc.

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