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.

A247076 Number of tilings of a 5 X 2n rectangle using 2n pentominoes of shape P.

Original entry on oeis.org

1, 2, 6, 20, 62, 194, 612, 1922, 6038, 18980, 59646, 187442, 589076, 1851266, 5817894, 18283700, 57459518, 180575906, 567489348, 1783428098, 5604714422, 17613731780, 55354032894, 173959101458, 546694927604, 1718078222594, 5399341807686, 16968314698580
Offset: 0

Views

Author

Alois P. Heinz, Nov 17 2014

Keywords

Examples

			a(2) = 6:
._______. ._______. ._______. ._______. ._______. ._______.
|   |   | |   |   | |   |   | |   |   | |   ._| | | |_.   |
| ._| ._| |_. |_. | | ._|_. | |_. | ._| |___|   | |   |___|
|_| |_| | | |_| |_| |_| | |_| | |_|_| | |   |___| |___|   |
|   |   | |   |   | |   |   | |   |   | | ._|   | |   |_. |
|___|___| |___|___| |___|___| |___|___| |_|_____| |_____|_| .
		

Crossrefs

Even bisection of main diagonal of A247706.

Programs

  • Maple
    a:= proc(n) option remember; `if`(n<4, [1, 2, 6, 20][n+1],
           2*a(n-1) +2*a(n-2) +5*a(n-3))
        end:
    seq(a(n), n=0..40);
  • Mathematica
    Join[{1}, LinearRecurrence[{2, 2, 5}, {2, 6, 20}, 40]] (* Jean-François Alcover, May 29 2018 *)

Formula

G.f.: (x-1)*(x^2+x+1)/(5*x^3+2*x^2+2*x-1).
a(n) = 2*a(n-1)+2*a(n-2)+5*a(n-3) for n>3, a(0)=1; a(1)=2, a(2)=6, a(3)=20.

A247739 Total number of P shapes in all tilings of a 5 X n rectangle with pentominoes of any shape.

Original entry on oeis.org

0, 0, 4, 60, 556, 5328, 45316, 405636, 3583136, 30801264, 261702184, 2204389124, 18485952896, 154072120428, 1276431617512, 10525735832272, 86463238965520, 707822586795020, 5776135319900600, 47001025464956044, 381480686633266156, 3089168335328298424, 24963223479997963992
Offset: 0

Views

Author

Alois P. Heinz, Sep 23 2014

Keywords

Crossrefs

Formula

a(n) = Sum_{k>0} k * A247706(n,k).

A247770 Number of tilings of a 5 X n rectangle using n pentominoes of any but the P shape.

Original entry on oeis.org

1, 1, 3, 16, 135, 944, 4814, 26435, 158761, 978044, 5847896, 34112584, 200686378, 1192024482, 7093151801, 42038865123, 248625856115, 1472077262971, 8724918986240, 51715149361624, 306384777098954, 1814848220902299, 10751681585808618, 63702848673263049
Offset: 0

Views

Author

Alois P. Heinz, Sep 23 2014

Keywords

Crossrefs

Column k=0 of A247706.
Showing 1-5 of 5 results.