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 1-5 of 5 results.

A174249 Number of tilings of a 5 X n rectangle with n pentominoes of any shape.

Original entry on oeis.org

1, 1, 5, 56, 501, 4006, 27950, 214689, 1696781, 13205354, 101698212, 782267786, 6048166230, 46799177380, 361683136647, 2793722300087, 21583392631817, 166790059833039, 1288885349447958, 9959188643348952, 76953117224941654, 594617039453764617, 4594660583890506956
Offset: 0

Views

Author

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

Keywords

Crossrefs

Formula

a(n) ~ c * d^n, where d =
7.727036840800092392128639105511391434436212757335030092041375597587338371937..., c =
0.13364973920881772493778581621701653927538155984099992758656160782495174... (1/d is the root of the denominator, see g.f.). - Vaclav Kotesovec, May 19 2015

Extensions

a(0) prepended, a(11)-a(22) from Alois P. Heinz, Dec 05 2013

A233427 Number A(n,k) of tilings of a k X n rectangle using pentominoes 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, 0, 0, 1, 1, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 1, 1, 1, 0, 5, 0, 0, 5, 0, 1, 1, 0, 0, 56, 0, 56, 0, 0, 1, 1, 0, 0, 0, 501, 501, 0, 0, 0, 1, 1, 0, 0, 0, 0, 4006, 0, 0, 0, 0, 1, 1, 1, 0, 0, 0, 27950, 27950, 0, 0, 0, 1, 1, 1, 0, 45, 0, 0, 214689, 0, 214689, 0, 0, 45, 0, 1
Offset: 0

Views

Author

Alois P. Heinz, Dec 09 2013

Keywords

Examples

			A(5,2) = A(2,5) = 5:
  ._________. ._________. ._________. ._________. ._________.
  |_________| | ._____| | | |_____. | |   ._|   | |   |_.   |
  |_________| |_|_______| |_______|_| |___|_____| |_____|___|.
Square array A(n,k) begins:
  1, 1,  1,    1,      1,         1,          1, ...
  1, 0,  0,    0,      0,         1,          0, ...
  1, 0,  0,    0,      0,         5,          0, ...
  1, 0,  0,    0,      0,        56,          0, ...
  1, 0,  0,    0,      0,       501,          0, ...
  1, 1,  5,   56,    501,      4006,      27950, ...
  1, 0,  0,    0,      0,     27950,          0, ...
  1, 0,  0,    0,      0,    214689,          0, ...
  1, 0,  0,    0,      0,   1696781,          0, ...
  1, 0,  0,    0,      0,  13205354,          0, ...
  1, 1, 45, 7670, 890989, 101698212, 7845888732, ...
  ...
		

Crossrefs

Formula

A(n,k) = 0 <=> n*k mod 5 > 0.

A247744 Total number of X shapes in all tilings of a 5 X n rectangle with pentominoes of any shape.

Original entry on oeis.org

0, 0, 0, 1, 8, 76, 752, 7728, 76138, 683740, 6016612, 52483260, 453461612, 3873299197, 32718505462, 274368261226, 2287565667766, 18973561019204, 156622182476404, 1287479429817295, 10545476231546336, 86101164740284870, 700977394316933694, 5692064258367318333
Offset: 0

Views

Author

Alois P. Heinz, Sep 23 2014

Keywords

Crossrefs

Formula

a(n) = Sum_{k>0} k * A247711(n,k).

A247775 Number of tilings of a 5 X n rectangle using n pentominoes of any but the X shape.

Original entry on oeis.org

1, 1, 5, 55, 493, 3930, 27207, 207118, 1622723, 12544364, 95912510, 732066083, 5616480627, 43128778000, 330817187318, 2536012919124, 19443866141395, 149118307026576, 1143608532988558, 8769818352137034, 67250342436670138, 515711365536657077, 3954797365004436075
Offset: 0

Views

Author

Alois P. Heinz, Sep 23 2014

Keywords

Crossrefs

Column k=0 of A247711.

A247828 Number of tilings of a 5 X n rectangle using n pentominoes of any shape including exactly one X shape.

Original entry on oeis.org

0, 0, 0, 1, 8, 76, 734, 7414, 71986, 638499, 5558790, 47971603, 410502410, 3473846885, 29078659564, 241699322196, 1997778940804, 16429720592636, 134489816829048, 1096404231410945, 8906880161717904, 72131791267258552, 582512418898356698, 4692186192041626600
Offset: 0

Views

Author

Alois P. Heinz, Sep 24 2014

Keywords

Examples

			a(3) = 1:
._____.
| ._. |
|_| |_|
|_. ._|
| |_| |
|_____| .
		

Crossrefs

Column k=1 of A247711.
Showing 1-5 of 5 results.