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 11-17 of 17 results.

A174252 Number of tilings of an 8 X n rectangle with n octominoes of any shape.

Original entry on oeis.org

1, 1, 8, 546, 39731, 2152050, 99697633, 4292655082, 187497290034, 8378760802160, 385296986628990
Offset: 0

Views

Author

Bob Harris (me13013(AT)gmail.com), Mar 13 2010

Keywords

Crossrefs

A174253 Number of tilings of a 9 X n rectangle with n nonominoes of any shape.

Original entry on oeis.org

1, 1, 9, 1095, 145415, 15661597, 1418159011, 112976454947, 8812020831683, 706152947468301, 58015563977931125
Offset: 0

Views

Author

Bob Harris (me13013(AT)gmail.com), Mar 13 2010

Keywords

Crossrefs

A232684 Number of tilings of a 6 X 2n rectangle with 3n tetrominoes of any shape.

Original entry on oeis.org

1, 9, 2003, 178939, 22483347, 2569437089, 304446920314, 35704534261665, 4203065267122878, 494232382069456694, 58138539945306221167, 6838279451118114249916, 804352962762109905924360, 94610929453211737452277488, 11128526714790919845521179844
Offset: 0

Views

Author

Alois P. Heinz, Nov 27 2013

Keywords

Examples

			a(1) = 9:
.___. .___. .___. .___. .___. .___. .___. .___. .___.
|   | | | | |   | |_. | |   | | ._| |   | | ._| |_. |
|___| | | | |___| | | | |___| | | | |___| | | | | | |
|   | | | | | | | | |_| |_. | |_| | | ._| |_| | | |_|
|___| |_|_| | | | |___| | | | |___| | | | | | | | | |
|   | |   | | | | |   | | |_| |   | |_| | | |_| |_| |
|___| |___| |_|_| |___| |___| |___| |___| |___| |___|.
		

Crossrefs

Even bisection of column k=6 of A230031.

A232698 Number of tilings of an 8 X n rectangle with 2n tetrominoes of any shape.

Original entry on oeis.org

1, 1, 25, 997, 40899, 800290, 22483347, 657253434, 19077209438, 517312744806, 14571957312254, 412240433359025, 11632857444709188, 326275845576101452, 9187549952207915190, 258821654387452112268, 7288072624408347082481, 205113474464891986564786
Offset: 0

Views

Author

Alois P. Heinz, Nov 27 2013

Keywords

Crossrefs

Column k=8 of A230031.

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.

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).
Previous Showing 11-17 of 17 results.