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.

A364457 Number A(n,k) of tilings of a k X n rectangle using dominoes and trominoes (of any shape); square array A(n,k), n>=0, k>=0, read by antidiagonals.

Original entry on oeis.org

1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 6, 6, 1, 1, 1, 2, 17, 30, 17, 2, 1, 1, 2, 43, 145, 145, 43, 2, 1, 1, 3, 108, 733, 1352, 733, 108, 3, 1, 1, 4, 280, 3540, 12688, 12688, 3540, 280, 4, 1, 1, 5, 727, 17300, 115958, 226922, 115958, 17300, 727, 5, 1
Offset: 0

Views

Author

Alois P. Heinz, Jul 25 2023

Keywords

Examples

			A(3,2) = A(2,3) = 6:
  .___.   .___.   .___.   .___.   .___.   .___.
  | | |   |___|   | | |   |___|   | ._|   |_. |
  | | |   |___|   |_|_|   | | |   |_| |   | |_|
  |_|_|   |___|   |___|   |_|_|   |___|   |___|  .
.
Square array A(n,k) begins:
  1, 1,   1,     1,       1,        1,          1,            1, ...
  1, 0,   1,     1,       1,        2,          2,            3, ...
  1, 1,   2,     6,      17,       43,        108,          280, ...
  1, 1,   6,    30,     145,      733,       3540,        17300, ...
  1, 1,  17,   145,    1352,    12688,     115958,      1075397, ...
  1, 2,  43,   733,   12688,   226922,    3927233,     68846551, ...
  1, 2, 108,  3540,  115958,  3927233,  128441094,   4263997124, ...
  1, 3, 280, 17300, 1075397, 68846551, 4263997124, 267855152858, ...
		

Crossrefs

Columns (or rows) k=0-10 give: A000012, A182097(n) = A000931(n+3), A019439, A364460, A364155, A364556, A364616, A364617, A364632, A364638, A364640.
Main diagonal gives A364504.

Formula

A(n,k) = A(k,n).

Extensions

Terms n,k>=4 had to be corrected as was pointed out by Martin Fuller and David Radcliffe - Alois P. Heinz, Apr 05 2025

A219994 Number of tilings of an n X n square using dominoes and right trominoes.

Original entry on oeis.org

1, 0, 2, 8, 380, 21272, 5350806, 3238675344, 6652506271144, 38896105985522272, 711716770252031164458, 38776997923112110535353528, 6460929292946758939597712150496, 3245656750963660788826395580466708824, 4953412325525289651086730443567098343730966, 22873302288206466754758793232467436030071524731072
Offset: 0

Views

Author

Alois P. Heinz, Dec 02 2012

Keywords

Examples

			a(3) = 8, because there are 8 tilings of a 3 X 3 square using dominoes and right trominoes:
  .___._.   .___._.   .___._.   .___._.
  |___| |   |___| |   |___| |   |_. | |
  | ._|_|   | | |_|   | |___|   | |_|_|
  |_|___|   |_|___|   |_|___|   |_|___|
  ._.___.   ._.___.   ._.___.   ._.___.
  | |___|   | | ._|   | |___|   | |___|
  |___| |   |_|_| |   |_|_. |   |_| | |
  |___|_|   |___|_|   |___|_|   |___|_|  .
		

Crossrefs

Main diagonal of A219987.

A219874 Number of tilings of an n X n square using dominoes and straight (3 X 1) trominoes.

Original entry on oeis.org

1, 0, 2, 14, 184, 9612, 1143834, 354859954, 295743829064, 631206895803116, 3541054185616706122, 51821077154605344550820, 1976225122734369352127065686, 196913655491597719598898811003348, 51179690353659852099434654264900753288, 34716223657627061096793572212632925410608268
Offset: 0

Views

Author

Alois P. Heinz, Nov 30 2012

Keywords

Examples

			a(3) = 14, because there are 14 tilings of a 3 X 3 square using dominoes and straight (3 X 1) trominoes:
  ._____. ._____. ._____. ._____. .___._. .___._. .___._.
  | | | | | | | | | |___| | |___| | | | | |___| | |___| |
  | | | | | |_|_| | |___| | | | | |_|_| | |___| | | | | |
  |_|_|_| |_|___| |_|___| |_|_|_| |___|_| |___|_| |_|_|_|
  ._____. ._____. ._____. ._____. ._____. ._____. ._____.
  |_____| |_____| |_____| |_____| | |___| | | | | |___| |
  |_____| | |___| | | | | |___| | |_|___| |_|_|_| |___|_|
  |_____| |_|___| |_|_|_| |___|_| |_____| |_____| |_____|  .
		

Crossrefs

Main diagonal of A219866.

Extensions

a(12) from Alois P. Heinz, Sep 30 2014
a(13)-a(15) (using Liang Kai's terms in A219866) from Alois P. Heinz, Mar 12 2025
Showing 1-3 of 3 results.