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 11-19 of 19 results.

A232722 Number of tilings of a 10 X 2n rectangle with 5n tetrominoes of any shape.

Original entry on oeis.org

1, 64, 796558, 2569437089, 14571957312254, 72713560548906621, 384821695402098361211, 2010131712836219582393758, 10562717745357186307808646827, 55429948254413509959115263015669, 291053238120184913211835376456587574, 1528063805458061047577398579978736135916
Offset: 0

Views

Author

Alois P. Heinz, Nov 28 2013

Keywords

Crossrefs

Even bisection of column k=10 of A230031.

A233139 Number of tilings of a 4 X n rectangle using T and Z tetrominoes.

Original entry on oeis.org

1, 0, 0, 0, 2, 4, 8, 18, 44, 104, 242, 564, 1320, 3090, 7228, 16904, 39538, 92484, 216328, 506002, 1183564, 2768424, 6475506, 15146580, 35428712, 82869778, 193837148, 453396168, 1060519538, 2480615780, 5802302024, 13571915922, 31745486700, 74254506984
Offset: 0

Views

Author

Alois P. Heinz, Dec 04 2013

Keywords

Examples

			a(5) = 4:
._____.___.  .___._____.  ._._____._.  ._._____._.
|_. ._| ._|  |_. |_. ._|  | |_. ._| |  | |_. ._| |
| |_|___| |  | |___|_| |  | ._|_|_. |  | ._|_|_. |
| ._| |_. |  | ._| |_. |  |_| |_. |_|  |_| ._| |_|
|_|_____|_|  |_|_____|_|  |_____|___|  |___|_____|.
		

Crossrefs

Programs

  • Maple
    a:= n-> (<<0|1|0|0>, <0|0|1|0>, <0|0|0|1>, <2|1|0|2>>^n.
            <<1, 0, 0, 0>>)[1, 1]:
    seq(a(n), n=0..40);

Formula

G.f.: (x^3+2*x-1) / (2*x^4+x^3+2*x-1).
a(n) = 2*a(n-1)+a(n-3)+2*a(n-4) for n>3, a(0)=1, a(1)=a(2)=a(3)=0.

A360498 Number of ways to tile an n X n square using oblongs with distinct dimensions.

Original entry on oeis.org

0, 0, 4, 12, 256, 3620, 87216, 2444084, 87181220
Offset: 1

Views

Author

Scott R. Shannon, Feb 09 2023

Keywords

Comments

All possible tilings are counted, including those identical by symmetry. Note that distinct dimensions means that, for example, a 1 x 3 oblong can only be used once, regardless of if it lies horizontally or vertically.

Examples

			a(1) = 0 as no distinct oblongs can tile a square with dimensions 1 x 1.
a(2) = 0 as no distinct oblongs can tile a square with dimensions 2 x 2.
a(3) = 4. There is one tiling, excluding those equivalent by symmetry:
.
  +---+---+---+
  |           |
  +---+---+---+
  |           |
  +           +
  |           |
  +---+---+---+
.
This tiling can occur in 4 different ways, giving 4 ways in total.
a(4) = 12. The possible tilings, excluding those equivalent by symmetry, are:
.
  +---+---+---+---+   +---+---+---+---+
  |   |           |   |               |
  +   +           +   +---+---+---+---+
  |   |           |   |               |
  +---+---+---+---+   +               +
  |               |   |               |
  +               +   +               +
  |               |   |               |
  +---+---+---+---+   +---+---+---+---+
.
The first tiling can occur in 8 different way and the second in 4 different ways, giving 12 ways in total.
		

Crossrefs

Cf. A360499 (rectangles), A004003, A099390, A065072, A233320, A230031.

A232757 Number of tilings of a 3 X 4n rectangle with 3n tetrominoes of any shape.

Original entry on oeis.org

1, 23, 997, 44855, 2023309, 91286913, 4118731453, 185831471351, 8384460804153, 378295365602127, 17068167803123941, 770092310699262519, 34745508355302417387, 1567669659985973646979, 70731103937531908893003, 3191290354032154992708783, 143986641757115568305530757
Offset: 0

Views

Author

Alois P. Heinz, Nov 29 2013

Keywords

Examples

			a(1) = 23:
._______. ._______. ._______. ._______. ._______. ._______.
| .___| | |_______| | |___. | |_______| | |   | | | ._|_. |
|_|_____| | .___| | |_____|_| | |___. | | |___| | | |   | |
|_______| |_|_____| |_______| |_____|_| |___|___| |_|___|_|
._______. ._______. ._______. ._______. ._______. ._______.
| ._|   | | | .___| |   |_. | |___. | | |   |   | |_______|
| | |___| | |_|   | |___| | | |   |_| | |___|___| |   |   |
|_|_____| |___|___| |_____|_| |___|___| |_______| |___|___|
._______. ._______. ._______. ._______. ._______. ._______.
| ._| ._| | |___. | |_. |_. | | .___| | | ._| | | | | |_. |
| |___| | | |_. |_| | |___| | |_| ._| | | |  _| | | |_. | |
|_|_____| |___|___| |_____|_| |___|___| |_|_|___| |___|_|_|
._______. ._______. ._______. ._______. ._______.
|_. ._| | | |_. ._| | .___| | | |___. | |_______|
| |_|_. | | ._|_| | |_| |_. | | ._| |_| |_______|
|_____|_| |_|_____| |_____|_| |_|_____| |_______|.
		

Crossrefs

Quadrisection of column k=3 of A230031.

Formula

G.f.: -(x^9 -29*x^8 +291*x^7 -1336*x^6 +2960*x^5 -3174*x^4 +1591*x^3 -372*x^2 +37*x-1) / (x^10 -36*x^9 +470*x^8 -2809*x^7 +8422*x^6 -12960*x^5 +10223*x^4 -3991*x^3 +755*x^2 -60*x+1).

A232758 Number of tilings of a 5 X 4n rectangle with 5n tetrominoes of any shape.

Original entry on oeis.org

1, 454, 800290, 1601437357, 3241461223149, 6567785027546670, 13308739956169022829, 26968602201880345700924, 54648749693738816337819872, 110739369582262512718466467943, 224400523235840773380469046439552, 454721704049686545819883721501971896
Offset: 0

Views

Author

Alois P. Heinz, Nov 29 2013

Keywords

Crossrefs

Quadrisection of column k=5 of A230031.

A232759 Number of tilings of a 7 X 4n rectangle with 7n tetrominoes of any shape.

Original entry on oeis.org

1, 9157, 657253434, 58480141962875, 5316709999497259059, 484393789403397886429249, 44141190389848159904786733934, 4022519784390988451174562198889336, 366566828291367228800261059891047626895, 33404748935117787113145811582089363383972226
Offset: 0

Views

Author

Alois P. Heinz, Nov 29 2013

Keywords

Crossrefs

Quadrisection of column k=7 of A230031.

A242636 Number of tilings of a 4 X n rectangle using tetrominoes of shapes L, Z, O.

Original entry on oeis.org

1, 0, 3, 12, 23, 94, 289, 842, 2771, 8510, 26411, 83122, 258199, 805914, 2517287, 7846960, 24490017, 76416244, 238387767, 743840496, 2320800841, 7240890040, 22592311143, 70488834118, 219928631821, 686190651342, 2140948175385, 6679872756528, 20841562274863
Offset: 0

Views

Author

Alois P. Heinz, May 19 2014

Keywords

Examples

			a(3) = 12:
._____.  ._____.  .___._.  ._.___.  ._____.  ._____.
| .___|  |___. |  |   | |  | |   |  |___. |  | .___|
|_|_. |  | ._|_|  |___| |  | |___|  |   |_|  |_|   |
|   | |  | |   |  | |___|  |___| |  |___| |  | |___|
|___|_|  |_|___|  |_____|  |_____|  |_____|  |_____|
._____.  ._____.  ._.___.  .___._.  ._____.  ._____.
| .___|  |___. |  | |_. |  | ._| |  | .___|  |___. |
|_| ._|  |_. |_|  |_. | |  | | ._|  |_| | |  | | |_|
|___| |  | |___|  | |_|_|  |_|_| |  | ._| |  | |_. |
|_____|  |_____|  |_____|  |_____|  |_|___|  |___|_|.
		

Crossrefs

Programs

  • Maple
    gf:= (x^6-x^5-2*x^4+x^3+3*x^2-1) / (-2*x^12 -4*x^10 -2*x^9 +x^8 -3*x^7 -13*x^6 -18*x^5 +3*x^4 +13*x^3 +6*x^2 -1):
    a:= n-> coeff(series(gf, x, n+1), x, n):
    seq(a(n), n=0..40);

Formula

G.f.: (x^6-x^5-2*x^4+x^3+3*x^2-1) / (-2*x^12 -4*x^10 -2*x^9 +x^8 -3*x^7 -13*x^6 -18*x^5 +3*x^4 +13*x^3 +6*x^2 -1).

A247113 Number of tilings of a 9 X 4n rectangle with 9n tetrominoes of any shape.

Original entry on oeis.org

1, 179399, 517312744806, 2045387873615550415, 8355513115448789147187273, 34243737232278596352691552132065, 140387532129057613906130882433658669281, 575558645377903777492614229836093710424726422, 2359673678366714374809214450385908918997931183691473
Offset: 0

Views

Author

Alois P. Heinz, Nov 19 2014

Keywords

Crossrefs

Quadrisection of column k=9 of A230031.

A263425 Number of tilings of an 2n X 2n square using tetrominoes of any shape.

Original entry on oeis.org

1, 1, 117, 178939, 19077209438, 72713560548906621, 13664822582333502156627512
Offset: 0

Views

Author

Alois P. Heinz, Oct 17 2015

Keywords

Crossrefs

Bisection (even part) of main diagonal of A230031.
Cf. A004003.

Formula

a(n) = A230031(2n,2n).

Extensions

a(6) (using terms from A230031) from Alois P. Heinz, Mar 26 2025
Previous Showing 11-19 of 19 results.