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 11-18 of 18 results.

A121197 Consider the tiling of the plane with squares of two different sizes as in Fig. 2.4.2(g) of Grünbaum and Shephard, p. 74. a(n) is the number of connected figures that can be formed on this tiling, from any n squares.

Original entry on oeis.org

2, 2, 8, 34, 158, 777, 4006, 21224, 114348, 624222, 3441050, 19121530, 106957272
Offset: 1

Views

Author

N. J. A. Sloane, Aug 17 2006

Keywords

Comments

The Zucca web site calls these figures "n-DifferentSquares".
Also the number of one-sided polyforms on the faces of the truncated square tiling. - Peter Kagey, May 24 2025

References

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

Crossrefs

Extensions

More terms from Don Reble, Aug 17 2007
a(13) from Joseph Myers, Oct 06 2011

A344213 Number of generalized polyforms on the truncated trihexagonal tiling with n cells.

Original entry on oeis.org

1, 3, 3, 14, 50, 261, 1397, 8364, 50643, 315512, 1984853, 12619579, 80802300, 520724842, 3373646060, 21959949924, 143527242317
Offset: 0

Views

Author

Peter Kagey, May 11 2021

Keywords

Comments

This sequence counts "free" polyforms where holes are allowed. This means that two polyforms are considered the same if one is a rigid transformation (translation, rotation, reflection or glide reflection) of the other.

Crossrefs

Analogous for other tilings: A000105 (square), A000228 (hexagonal), A000577 (triangular), A197156 (prismatic pentagonal), A197159 (floret pentagonal), A197459 (rhombille), A197462 (kisrhombille), A197465 (tetrakis square), A309159 (snub square), A343398 (trihexagonal), A343406 (truncated hexagonal), A343577 (truncated square), A344211 (rhombitrihexagonal).

Extensions

a(10)-a(16) from Bert Dobbelaere, Jun 07 2025

A383908 Number of generalized polyforms with n cells on the snub trihexagonal tiling.

Original entry on oeis.org

1, 3, 3, 7, 23, 69, 228, 766, 2642, 9309, 33382, 120629, 439752, 1613135, 5953061, 22075011, 82204128, 307213215, 1151820825, 4330858682, 16326297768, 61690058385
Offset: 0

Views

Author

Peter Kagey, May 14 2025

Keywords

Comments

A generalized polyform on the snub trihexagonal tiling with n-cells is a collection of n faces connected edgewise. Two polyforms are considered the same they are related by an isometry (translation and/or rotation) of the snub trihexagonal tiling.

Examples

			For n=1, the a(1) = 3 generalized polyforms are the three types of faces: hexagons, hexagon-adjacent triangles, and hexagon-nonadjacent triangles.
For n=2, the a(2) = 3 generalized polyforms are
(1) a hexagon with a hexagon-adjacent triangle,
(2) a hexagon-adjacent triangle with a hexagon-nonadjacent triangle, and
(3) two hexagon-adjacent triangles.
		

Crossrefs

Analogous for other tilings: A000105 (square), A000228 (hexagonal), A000577 (triangular), A197156 (prismatic pentagonal), A197159 (floret pentagonal), A197459 (rhombille), A197462 (kisrhombille), A197465 (tetrakis square), A309159 (snub square), A343398 (trihexagonal), A343406 (truncated hexagonal), A343577 (truncated square), A344211 (rhombitrihexagonal), A344213 (truncated trihexagonal).

Extensions

a(12)-a(21) from Bert Dobbelaere, Jun 05 2025

A343417 a(n) is the number of free polyominoes with k cells and n-k distinguished vertices.

Original entry on oeis.org

1, 1, 2, 6, 19, 71, 300, 1370, 6563, 32272, 161700, 820166, 4198764, 21647353, 112262033, 585049063, 3061951973, 16084816384, 84773694223
Offset: 0

Views

Author

Peter Kagey, Apr 15 2021

Keywords

Comments

This sequence counts "free" polyominoes where holes are allowed. This means that two polyominoes are considered the same if one is a rigid transformation (translation, rotation, reflection or glide reflection) of the other.
A000105(n) <= a(n) <= A343577(n).
For an ordinary, asymmetrical polyomino, the number of free polyominoes with d distinguished cells is equal to C(v,d), where v is the number of vertices of the polyomino, and C is the binomial coefficient (A007318). - John Mason, Mar 11 2022

Examples

			For n = 3, the a(3) = 6 polyominoes with k cells and 3-k distinguished vertices are:
+---+                     *---+  +---+
|   |                     |   |  |   |
+   +---+  +---+---+---+  +   +  *   +  *---+  *---+
|       |  |           |  |   |  |   |  |   |  |   |
+---+---+, +---+---+---+, +---+, +---+, *---+, +---*,
where distinguished vertices are marked with asterisks.
For n = 4, a(4) = 19 because there are A000105(4) = 5 polyominoes with four cells and no distinguished vertices, 7 polyominoes with three cells and one distinguished vertex, 6 polyominoes with two cells and two distinguished vertices, and 1 polyomino with one cell and three distinguished vertices.
		

Crossrefs

Extensions

a(11)-a(18) from John Mason, Mar 11 2022

A385265 Number of edge-connected components of polygonal cells in the pinwheel tiling up to rotation of the tiling.

Original entry on oeis.org

1, 2, 4, 13, 53, 209, 904, 3963, 17900, 81745, 378554, 1768236, 8327789, 39471091, 188145066, 901117082, 4334151970, 20923370406, 101341800704, 492289834345
Offset: 0

Views

Author

Peter Kagey and Bert Dobbelaere, Jun 23 2025

Keywords

Comments

These are "one-sided" polyforms because there are no reflectional symmetries of the pinwheel tiling.
Here the "pinwheel tiling" is a tiling consisting of rectangular and square cells, and does not refer to non-periodic triangular tilings.

Crossrefs

A000105 (square), A000228 (hexagonal), A000577 (triangular), A197156 (prismatic pentagonal), A197159 (floret pentagonal), A197459 (rhombille), A197462 (kisrhombille), A197465 (tetrakis square), A309159 (snub square), A343398 (trihexagonal), A343406 (truncated hexagonal), A343577 (truncated square), A344211 (rhombitrihexagonal), A344213 (truncated trihexagonal), A383908 (snub trihexagonal), A385266 (basketweave).

A385266 Number of edge-connected components of polygonal cells in the basketweave tiling up to rotation and reflection of the tiling.

Original entry on oeis.org

1, 2, 2, 10, 34, 166, 777, 4053, 21225, 114594, 624242, 3442399, 19121661, 106964679, 601639326, 3400619170, 19301719485, 109962791254
Offset: 0

Views

Author

Peter Kagey and Bert Dobbelaere, Jun 23 2025

Keywords

Comments

Each square cell in the basketweave tiling is edge-connected to four rectangular cells.

Crossrefs

A000105 (square), A000228 (hexagonal), A000577 (triangular), A197156 (prismatic pentagonal), A197159 (floret pentagonal), A197459 (rhombille), A197462 (kisrhombille), A197465 (tetrakis square), A309159 (snub square), A343398 (trihexagonal), A343406 (truncated hexagonal), A343577 (truncated square), A344211 (rhombitrihexagonal), A344213 (truncated trihexagonal), A383908 (snub trihexagonal), A385265 (pinwheel).

A057707 a(n) is the number of free 'polyominoes' on the (4.8.8) grid with n octagons and n squares.

Original entry on oeis.org

1, 8, 80, 1296, 22601, 426305, 8340302, 167925635, 3453618607
Offset: 1

Views

Author

Warren Power (wjpnply(AT)hotmail.com), Oct 24 2000

Keywords

Comments

This sequence enumerates a subset of the polyforms enumerated by A343577. - John Mason, Jan 15 2023

Crossrefs

Cf. A343577.

Extensions

Better description from Larry Reeves (larryr(AT)acm.org), Nov 30 2000
a(6)-a(8) from John Mason, Jan 15 2023
a(9) from John Mason, Mar 01 2023

A345076 Number of generalized polyforms on the elongated triangular tiling with n cells.

Original entry on oeis.org

1, 2, 3, 5, 13, 32, 96, 283, 907, 2929, 9787, 32939, 112476, 386230, 1336150, 4642930, 16208851, 56786242, 199614651, 703678568, 2487109359, 8811020024, 31281360326, 111272475650
Offset: 0

Views

Author

Drake Thomas, Jun 07 2021

Keywords

Comments

This sequence counts free polyforms where holes are allowed. This means that two polyforms are considered the same if one is a rigid transformation (translation, rotation, reflection or glide reflection) of the other.

Examples

			See the PDF in the links section.
		

Crossrefs

Analogous for other tilings: A000105 (square), A000228 (hexagonal), A000577 (triangular), A197156 (prismatic pentagonal), A197159 (floret pentagonal), A197459 (rhombille), A197462 (kisrhombille), A197465 (tetrakis square), A309159 (snub square), A343398 (trihexagonal), A343406 (truncated hexagonal), A343577 (truncated square).

Extensions

a(15)-a(23) from Bert Dobbelaere, Jun 05 2025
Previous Showing 11-18 of 18 results.