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 1-9 of 9 results.

A174248 Number of tilings of a 4 X n rectangle with n tetrominoes of any shape.

Original entry on oeis.org

1, 1, 4, 23, 117, 454, 2003, 9157, 40899, 179399, 796558, 3546996, 15747348, 69834517, 310058192, 1376868145, 6112247118, 27132236455, 120453362938, 534754586459, 2373975139658, 10538953415410, 46786795734201, 207705902269424, 922089495910044, 4093525019450760
Offset: 0

Views

Author

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

Keywords

Crossrefs

Formula

G.f.: -(x^31 +3*x^30 -2*x^29 -7*x^28 -25*x^27 -78*x^26 +23*x^25 +116*x^24 +217*x^23 +604*x^22 -21*x^21 -556*x^20 -649*x^19 -1621*x^18 -175*x^17 +727*x^16 +523*x^15 +1707*x^14 +236*x^13 -470*x^12 -143*x^11 -749*x^10 -133*x^9 +166*x^8 +15*x^7 +126*x^6 +27*x^5 -23*x^4 -x^3 -6*x^2 -x +1) / (x^35 +3*x^34 -3*x^33 -13*x^32 -50*x^31 -123*x^30 +39*x^29 +225*x^28 +659*x^27 +1476*x^26 +60*x^25 -1102*x^24 -2600*x^23 -6047*x^22 -489*x^21 +2786*x^20 +3210*x^19 +9566*x^18 +1102*x^17 -3349*x^16 -1620*x^15 -6885*x^14 -1053*x^13 +1970*x^12 +414*x^11 +2258*x^10 +469*x^9 -548*x^8 -76*x^7 -290*x^6 -77*x^5 +54*x^4 +8*x^3 +8*x^2 +2*x -1). - Alois P. Heinz, Nov 26 2013

Extensions

a(0) inserted, a(11)-a(22) from Alois P. Heinz, May 07 2013
a(23)-a(25) from Alois P. Heinz, Nov 26 2013

A084480 Number of tilings of a 4 X 2n rectangle with L tetrominoes.

Original entry on oeis.org

1, 2, 10, 42, 182, 790, 3432, 14914, 64814, 281680, 1224182, 5320310, 23122148, 100489226, 436727814, 1898026232, 8248853134, 35849651070, 155803171860, 677123141810, 2942788286798, 12789406189672, 55582969192486, 241564496305670, 1049843265359828
Offset: 0

Views

Author

Ralf Stephan, May 27 2003

Keywords

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{4, 2, -1, -4, -4, -2}, {1, 2, 10, 42, 182, 790}, 25] (* Jean-François Alcover, Feb 25 2020 *)
  • PARI
    Vec((1 - 2*x - x^3) / (1 - 4*x - 2*x^2 + x^3 + 4*x^4 + 4*x^5 + 2*x^6) + O(x^30)) \\ Colin Barker, Mar 28 2017

Formula

G.f.: (1-2*z-z^3) / (1-4*z-2*z^2+z^3+4*z^4+4*z^5+2*z^6).
a(n) = 4*a(n-1) + 2*a(n-2) - a(n-3) - 4*a(n-4) - 4*a(n-5) - 2*a(n-6) for n>5. - Colin Barker, Mar 28 2017

Extensions

Inserted a(0)=1 by Alois P. Heinz, May 01 2013

A165791 Number of tilings of a 4 X n rectangle using dominoes and right trominoes.

Original entry on oeis.org

1, 1, 11, 55, 380, 2319, 15171, 96139, 619773, 3962734, 25445515, 163048957, 1045897075, 6705473761, 43001795070, 275730928993, 1768128097215, 11337760387473, 72702310606249, 466192677008538, 2989403530821497, 19169143325987983, 122919655766448729
Offset: 0

Views

Author

Alois P. Heinz, Sep 26 2009

Keywords

Examples

			a(2) = 11, because there are 11 tilings of a 4 X 2 rectangle using dominoes and right trominoes:
  .___. .___. .___. ._._. ._._. .___. .___. .___. .___. .___. .___.
  |___| |___| |_._| | | | | | | |___| |___| | ._| |_. | | ._| |_. |
  |___| |_._| | | | |_|_| |_|_| | ._| |_. | |_| | | |_| |_| | | |_|
  |___| | | | |_|_| |___| | | | |_| | | |_| |___| |___| | |_| |_| |
  |___| |_|_| |___| |___| |_|_| |___| |___| |___| |___| |___| |___|  .
		

Crossrefs

Column k=4 of A219987.

Programs

  • Maple
    a:= n-> (Matrix([[619773, 96139, 15171, 2319, 380, 55, 11, 1, 1]]). Matrix(9, (i,j)-> if i=j-1 then 1 elif j=1 then [4, 21, -25, -65, -17, 24, -11, -15, 9][i] else 0 fi)^n)[1,9]: seq(a(n), n=0..25);
  • Mathematica
    a[n_] := {619773, 96139, 15171, 2319, 380, 55, 11, 1, 1} . MatrixPower[ Table[ Which[i == j-1, 1, j == 1, {4, 21, -25, -65, -17, 24, -11, -15, 9}[[i]], True, 0], {i, 1, 9}, {j, 1, 9}], n] // Last; Table[a[n], {n, 0, 25}] (* Jean-François Alcover, Dec 04 2013, translated and adapted from Alois P. Heinz's Maple program *)

Formula

G.f.: (2*x^8-5*x^7+2*x^6-x^5-19*x^4-15*x^3+14*x^2+3*x-1) / (9*x^9-15*x^8-11*x^7+24*x^6-17*x^5-65*x^4-25*x^3+21*x^2+4*x-1).

A232497 Number of tilings of a 4 X n rectangle using L and Z tetrominoes.

Original entry on oeis.org

1, 0, 2, 6, 14, 32, 102, 238, 652, 1696, 4480, 11658, 30870, 80644, 212292, 556858, 1463390, 3840686, 10090218, 26490280, 69575414, 182693434, 479789138, 1259906496, 3308668718, 8688615148, 22817011182, 59918425698, 157349755400, 413208421354, 1085110433096
Offset: 0

Views

Author

Alois P. Heinz, Nov 24 2013

Keywords

Examples

			a(3) = 6:
._._._.  ._._._.  ._._._.  ._._._.  ._._._.  ._._._.
| .___|  |___. |  | |_. |  | ._| |  | .___|  |___. |
|_| ._|  |_. |_|  |_. | |  | | ._|  |_| | |  | | |_|
|___| |  | |___|  | |_|_|  |_|_| |  | ._| |  | |_. |
|_____|  |_____|  |_____|  |_____|  |_|___|  |___|_|.
		

Crossrefs

Programs

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

A233191 Number of tilings of a 4 X n rectangle using L and T tetrominoes.

Original entry on oeis.org

1, 0, 2, 4, 12, 16, 76, 128, 386, 832, 2368, 5024, 13946, 31680, 82632, 193696, 498174, 1182464, 2993384, 7213648, 18061074, 43832960, 109163384, 266217472, 660116398, 1615451648, 3995295112, 9796774896, 24189684402, 59396496000, 146494223160, 360026507808
Offset: 0

Views

Author

Alois P. Heinz, Dec 05 2013

Keywords

Examples

			a(3) = 4:
._____.  ._____.  ._____.  ._____.
|_. ._|  |_. ._|  | |_. |  | ._| |
| |_| |  | |_| |  | ._| |  | |_. |
| ._| |  | |_. |  |_| |_|  |_| |_|
|_|___|  |___|_|  |_____|  |_____|.
		

Crossrefs

Programs

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

Formula

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

A233266 Number of tilings of a 4 X n rectangle using tetrominoes of shapes L, T, Z.

Original entry on oeis.org

1, 0, 2, 10, 24, 70, 276, 820, 2616, 8702, 27902, 89500, 291050, 939222, 3029950, 9798606, 31657182, 102237766, 330356240, 1067310022, 3447911968, 11139391996, 35988377472, 116265759012, 375619824338, 1213515477460, 3920484872552, 12665878390278
Offset: 0

Views

Author

Alois P. Heinz, Dec 06 2013

Keywords

Examples

			a(3) = 10:
._____.  ._____.  ._____.  ._____.  ._____.
| |_. |  | ._| |  | .___|  |___. |  | .___|
|_. | |  | | ._|  |_| | |  | | |_|  |_| ._|
| |_|_|  |_|_| |  | ._| |  | |_. |  |___| |
|_____|  |_____|  |_|___|  |___|_|  |_____|
._____.  ._____.  ._____.  ._____.  ._____.
| ._| |  | |_. |  |_. ._|  |_. ._|  |___. |
| |_. |  | ._| |  | |_| |  | |_| |  |_. |_|
|_| |_|  |_| |_|  | |_. |  | ._| |  | |___|
|_____|  |_____|  |___|_|  |_|___|  |_____|.
		

Crossrefs

Formula

G.f.: (x^8 -4*x^7 +3*x^6 -2*x^5 -2*x^4 -2*x^3 +2*x^2 +2*x -1) / (-2*x^14 +8*x^13 -10*x^12 +16*x^11 -4*x^10 +20*x^9 -13*x^8 +4*x^7 +15*x^6 -28*x^5 -6*x^4 +4*x^3 +4*x^2 +2*x -1).

A165799 Number of tilings of a 4 X n rectangle using right trominoes and 2 X 2 tiles.

Original entry on oeis.org

1, 0, 1, 4, 6, 16, 37, 92, 245, 560, 1426, 3720, 9069, 22808, 58177, 145660, 366318, 925536, 2331269, 5872212, 14802941, 37311528, 94038250, 236999064, 597348237, 1505640016, 3794761257, 9564393972, 24106951622, 60759989040, 153141435269, 385986293964
Offset: 0

Views

Author

Alois P. Heinz, Sep 27 2009

Keywords

Examples

			a(4) = 6, because there are 6 tilings of a 4 X 4 rectangle using right trominoes and 2 X 2 tiles:
  .___.___. .___.___. .___.___. .___.___. .___.___. .___.___.
  | . | . | | ._|_. | | ._| . | | ._|_. | | ._|_. | | . |_. |
  |___|___| |_| . |_| |_| |___| |_| ._|_| |_|_. |_| |___| |_|
  | . | . | | |___| | | |___| | | |_| . | | . |_| | | |___| |
  |___|___| |___|___| |___|___| |___|___| |___|___| |___|___|
		

Crossrefs

Column k=4 of A219946.

Programs

  • Maple
    a:= n-> (Matrix([[4, 1, 0, 1, 0$5]]). Matrix(9, (i,j)-> if i=j-1 then 1 elif j=1 then [1, 1, 9, 1, -3, -22, -16, 0, -4][i] else 0 fi)^n)[1,4]: seq(a(n), n=0..30);
  • Mathematica
    Series[ (-6*x^3 - x + 1) / (4*x^9 + 16*x^7 + 22*x^6 + 3*x^5 - x^4 - 9*x^3 - x^2 - x + 1), {x, 0, 31}] // CoefficientList[#, x] & (* Jean-François Alcover, Jun 18 2013, after Alois P. Heinz *)
    LinearRecurrence[{1,1,9,1,-3,-22,-16,0,-4},{1,0,1,4,6,16,37,92,245},40] (* Harvey P. Dale, Nov 09 2024 *)

Formula

G.f.: -(6*x^3+x-1) / (4*x^9+16*x^7+22*x^6+3*x^5-x^4-9*x^3-x^2-x+1).
a(n) = a(n-1) +a(n-2) +9*a(n-3) +a(n-4) -3*a(n-5) -22*a(n-6) -16*a(n-7) -4*a(n-9).

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).
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