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 11-20 of 37 results. Next

A103468 Number of polyominoes consisting of n regular unit 10-gons.

Original entry on oeis.org

1, 1, 4, 19, 127, 985, 8350, 73675, 664411, 6078768, 56198759, 523924389, 4918127659
Offset: 1

Views

Author

Sascha Kurz, Feb 07 2005

Keywords

Crossrefs

Extensions

More terms from Sascha Kurz, Jun 09 2006

A120103 Number of polyominoes consisting of 9 regular unit n-gons.

Original entry on oeis.org

160, 1285, 14445, 6572, 14982, 65323, 280014, 664411, 1908239, 1314914, 1968684, 4158216, 9707046, 17054708, 33522023, 26019735, 33942901, 56537856, 100952307, 153177526, 251530341, 208524646, 254079408, 374310135, 586169115, 812395658
Offset: 3

Views

Author

Sascha Kurz, Jun 09 2006

Keywords

Examples

			a(3)=160 because there are 160 polyiamonds consisting of 9 triangles and a(4)=1285 because there are 1285 polyominoes consisting of 9 squares.
		

Crossrefs

A268371 Triangle read by rows: T(n,k) is the number of free polyominoes with width n and height 1<=k<=n.

Original entry on oeis.org

1, 1, 2, 1, 6, 24, 1, 12, 181, 1051, 1, 30, 941, 21992, 238048, 1, 65, 4662, 228013, 9735647, 195284973, 1, 158, 23691, 2337694, 195616247, 15256715219, 577169894573
Offset: 1

Views

Author

John Mason, Feb 03 2016

Keywords

Comments

Superset of Craig Knecht's A268311.

Examples

			The first rows of the array are:
1;
1, 2;
1, 6, 24;
1, 12, 181, 1051;
...
T(4,3)=181 = 15+39+59+42+21+4+1: In the 4x3 square fit 15 6-ominoes, 39 7-ominoes, 59 8-ominoes, 42 9-ominoes, 21 10-ominoes, 4 11-ominoes or 1 12-omino. - _R. J. Mathar_, Jun 07 2020
		

Crossrefs

Cf. A268311 (right diagonal), A335711 (column n=2), A000105 (free polyominoes), A292357 (equival. for fixed polys).

Extensions

a(16)-a(28) from Jean-Luc Manguin, May 25 2020

A103466 Number of polyominoes consisting of n regular unit octagons.

Original entry on oeis.org

1, 1, 3, 11, 50, 269, 1605, 10102, 65323, 430302, 2868320, 19299334, 130807068, 892075515, 6115673262
Offset: 1

Views

Author

Sascha Kurz, Feb 07 2005

Keywords

Crossrefs

Extensions

More terms from Sascha Kurz, Jun 09 2006
Definition corrected by John Mason and Sascha Kurz, Sep 20 2020

A103467 Number of polyominoes consisting of n regular unit 9-gons.

Original entry on oeis.org

1, 1, 3, 14, 82, 585, 4418, 34838, 280014, 2285047, 18838395, 156644526, 1311575691
Offset: 1

Views

Author

Sascha Kurz, Feb 07 2005

Keywords

Crossrefs

Extensions

More terms from Sascha Kurz, Jun 09 2006
Definition corrected by John Mason and Sascha Kurz, Sep 20 2020

A054361 Number of polyominoes with n cells without holes that do not tile the plane.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 3, 20, 198, 1390, 9474, 35488, 178448, 696371, 2721544, 10683110, 41334494, 155723774, 596182769, 2257379379, 8587521496, 32688629235, 124568505590, 475147925759, 1815832051949
Offset: 1

Views

Author

Joe Keane (jgk(AT)jgk.org)

Keywords

Examples

			a(7) = 3.
		

References

  • Posting by Glenn C. Rhoads (rhoads(AT)paul.rutgers.edu) to rec.puzzles, Feb 17 2000.

Crossrefs

Extensions

Corrected and extended by Joseph Myers, May 05 2002
More terms from Joseph Myers, Nov 04 2003
a(24) and a(25) from Joseph Myers, Nov 17 2010

A089458 Number of n-celled polyominoes with exactly 6 holes.

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, 64, 2131, 38022, 480713, 4872679, 42360239
Offset: 1

Views

Author

Joseph Myers, Nov 04 2003

Keywords

Crossrefs

Extensions

a(27)-a(28) from Tomás Oliveira e Silva's page added by Andrey Zabolotskiy, Oct 02 2022

A259088 Number of n-celled polyominoes which are of square type.

Original entry on oeis.org

1, 0, 1, 1, 6, 7, 25, 80, 255, 795, 2919, 10378, 36590, 130716, 480773, 1774714, 6543633, 24208803, 90331307, 339178346, 1277308160, 4819109576
Offset: 1

Views

Author

N. J. A. Sloane, Jun 18 2015

Keywords

Examples

			a(7) = 25 with 7 free 7-ominoes with a 3x3 hull and 18 with 4x4 hull. a(8) = 80 with 3 free 8-ominoes with a 3x3 hull and 77 with a 4x4 hull. a(9) = 255 with 1 free 9-omino in a 3x3 hull, 181 in a 4x4 hull and 73 in a 5x5 hull. - _R. J. Mathar_, May 24 2019
		

Crossrefs

Formula

a(n)+A259087(n) = A000105(n).

Extensions

a(15)-a(16) from R. J. Mathar, May 22 2019
a(17) from R. J. Mathar, May 27 2019
a(18)-a(22) from John Mason, Nov 19 2021

A342537 Number of free polyominoes with n cells having simply-connected interiors.

Original entry on oeis.org

1, 1, 2, 5, 12, 35, 108, 368, 1283, 4639, 17003, 63222, 236819, 893515, 3387953, 12904855, 49335965, 189243115
Offset: 1

Views

Author

Keywords

Comments

The polyominoes referred to in the definition are those having a single traceable perimeter. The definition therefore includes the heptomino with a hole, as in this case the border, although not self-avoiding (it meets itself at a corner) is still traceable; it excludes the square octomino with a hole, whose border consists of two distinct polygons. Thus starting from n=8, A000104(n) < a(n) < A000105(n).

Crossrefs

Cf. A000104 (free polyominoes without holes), A000105 (free polyominoes).

Extensions

a(17)-a(18) from John Mason, Jan 04 2023

A056880 Number of n-celled polyominoes without holes, symmetric about axis 2.

Original entry on oeis.org

0, 1, 1, 1, 1, 2, 3, 4, 4, 6, 10, 11, 16, 18, 33, 34, 56, 56, 110, 106, 193, 177, 372, 335, 662, 571, 1269, 1084, 2282, 1875, 4365, 3568, 7914, 6257, 15141, 11935, 27615, 21170, 52911, 40486, 96980, 72490, 186144, 138981, 342638, 250814, 658884, 482029, 1217327, 875697, 2345272, 1686803
Offset: 1

Views

Author

N. J. A. Sloane, Sep 03 2000

Keywords

Comments

In other words, free polyominoes, without holes, with both vertical and horizontal symmetries but no other. - John Mason, Oct 10 2022

Crossrefs

Cf. A000104, A056877 (with holes allowed).

Extensions

a(29)-a(52) from John Mason, Oct 10 2022
Previous Showing 11-20 of 37 results. Next