A063443
Number of ways to tile an n X n square with 1 X 1 and 2 X 2 tiles.
Original entry on oeis.org
1, 1, 2, 5, 35, 314, 6427, 202841, 12727570, 1355115601, 269718819131, 94707789944544, 60711713670028729, 69645620389200894313, 144633664064386054815370, 540156683236043677756331721, 3641548665525780178990584908643, 44222017282082621251230960522832336
Offset: 0
- Steven R. Finch, Mathematical Constants, Cambridge, 2003, p. 343
- Andrew Woods and Vaclav Kotesovec and Johan Nilsson, Table of n, a(n) for n = 0..40 (terms 0..21 from Andrew Woods, terms 22..24 from Vaclav Kotesovec and terms 25..40 from Johan Nilsson)
- Vaclav Kotesovec, Non-attacking chess pieces, 6ed, 2013, p. 68-69.
- R. J. Mathar, Tiling n x m rectangles with 1 x 1 and s x s squares, arXiv:1609.03964 [math.CO], 2016, Section 4.1.
- J. Nilsson, On Counting the Number of Tilings of a Rectangle with Squares of Size 1 and 2, Journal of Integer Sequences, Vol. 20 (2017), Article 17.2.2.
- Eric Weisstein's World of Mathematics, Independent Vertex Set
- Eric Weisstein's World of Mathematics, King Graph
- Eric Weisstein's World of Mathematics, Vertex Cover
-
Needs["LinearAlgebra`MatrixManipulation`"] Remove[mat] step[sa[rules1_, {dim1_, dim1_}], sa[rules2_, {dim2_, dim2_}]] := sa[Join[rules2, rules1 /. {x_Integer, y_Integer} -> {x + dim2, y}, rules1 /. {x_Integer, y_Integer} -> {x, y + dim2}], {dim1 + dim2, dim1 + dim2}] mat[0] = sa[{{1, 1} -> 1}, {1, 1}]; mat[1] = sa[{{1, 1} -> 1, {1, 2} -> 1, {2, 1} -> 1}, {2, 2}]; mat[n_] := mat[n] = step[mat[n - 2], mat[n - 1]]; A[n_] := mat[n] /. sa -> SparseArray; F[n_] := MatrixPower[A[n], n + 1][[1, 1]]; (* Mark McClure (mcmcclur(AT)bulldog.unca.edu), Mar 19 2006 *)
$RecursionLimit = 1000; Clear[a, b]; b[n_, l_List] := b[n, l] = Module[{m=Min[l], k}, If[m>0, b[n-m, l-m], If[n == 0, 1, k=Position[l, 0, 1, 1][[1, 1]]; b[n, ReplacePart[l, k -> 1]] + If[n>1 && k 2, k+1 -> 2}]], 0]]]]; a[n_] := a[n] = If[n<2, 1, b[n, Table[0, {n}]]]; Table[Print[a[n]]; a[n], {n, 0, 17}] (* Jean-François Alcover, Dec 11 2014, after Alois P. Heinz *)
2 more terms from Keith Schneider (kschneid(AT)bulldog.unca.edu), Mar 19 2006
A245013
Number A(n,k) of tilings of a k X n rectangle using 1 X 1 squares and 2 X 2 squares; square array A(n,k), n>=0, k>=0, read by antidiagonals.
Original entry on oeis.org
1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 1, 3, 3, 1, 1, 1, 1, 5, 5, 5, 1, 1, 1, 1, 8, 11, 11, 8, 1, 1, 1, 1, 13, 21, 35, 21, 13, 1, 1, 1, 1, 21, 43, 93, 93, 43, 21, 1, 1, 1, 1, 34, 85, 269, 314, 269, 85, 34, 1, 1, 1, 1, 55, 171, 747, 1213, 1213, 747, 171, 55, 1, 1
Offset: 0
A(3,3) = 5:
._._._. .___._. ._.___. ._._._. ._._._.
|_|_|_| | |_| |_| | |_|_|_| |_|_|_|
|_|_|_| |___|_| |_|___| |_| | | |_|
|_|_|_| |_|_|_| |_|_|_| |_|___| |___|_| .
Square array A(n,k) begins:
1, 1, 1, 1, 1, 1, 1, 1, ...
1, 1, 1, 1, 1, 1, 1, 1, ...
1, 1, 2, 3, 5, 8, 13, 21, ...
1, 1, 3, 5, 11, 21, 43, 85, ...
1, 1, 5, 11, 35, 93, 269, 747, ...
1, 1, 8, 21, 93, 314, 1213, 4375, ...
1, 1, 13, 43, 269, 1213, 6427, 31387, ...
1, 1, 21, 85, 747, 4375, 31387, 202841, ...
- Liang Kai, Antidiagonals n = 0..80, flattened (antidiagonals n = 0..45 from Alois P. Heinz)
- Kai Liang, Independent Set Enumeration in King Graphs by Tensor Network Contractions, arXiv:2505.12776 [math.CO], 2025. See p. 4.
- R. J. Mathar, Tiling n x m rectangles with 1 x 1 and s x s squares, arXiv:1609.03964 [math.CO], 2016.
- Johan Nilsson, On Counting the Number of Tilings of a Rectangle with Squares of Size 1 and 2, Journal of Integer Sequences, Vol. 20 (2017), Article 17.2.2.
Columns (or rows) k=0+1,2-10 give:
A000012,
A000045(n+1),
A001045(n+1),
A054854,
A054855,
A063650,
A063651,
A063652,
A063653,
A063654.
-
b:= proc(n, l) option remember; local m, k; m:= min(l[]);
if m>0 then b(n-m, map(x->x-m, l))
elif n=0 then 1
else for k while l[k]>0 do od; b(n, subsop(k=1, l))+
`if`(n>1 and k `if`(min(n, k)<2, 1, b(max(n, k), [0$min(n, k)])):
seq(seq(A(n, d-n), n=0..d), d=0..14);
-
b[n_, l_] := b[n, l] = Module[{m=Min[l], k}, If[m>0, b[n-m, l-m], If[n == 0, 1, k=Position[l, 0, 1, 1][[1, 1]]; b[n, ReplacePart[l, k -> 1]] + If[n>1 && k 2, k+1 -> 2}]], 0]]]]; A[n_, k_] := If[Min[n, k]<2, 1, b[Max[n, k], Table[0, {Min[n, k]}]]]; Table[Table[A[n, d-n], {n, 0, d}], {d, 0, 14}] // Flatten (* Jean-François Alcover, Dec 11 2014, after Alois P. Heinz *)
A226322
Number of tilings of a 4 X n rectangle using L tetrominoes and 2 X 2 tiles.
Original entry on oeis.org
1, 0, 3, 6, 19, 48, 141, 378, 1063, 2920, 8115, 22418, 62123, 171876, 475919, 1317250, 3646681, 10094356, 27943739, 77353070, 214129845, 592752572, 1640859689, 4542223926, 12573787053, 34806745800, 96352029241, 266721635838, 738338745535, 2043868995512
Offset: 0
a(3) = 6:
._____. ._____. .___._. ._.___. ._____. ._____.
| .___| |___. | | | | | | | |___. | | .___|
|_|_. | | ._|_| |___| | | |___| | |_| |_| |
| | | | | | | |___| |___| | |___| | | |___|
|___|_| |_|___| |_____| |_____| |_____| |_____|
- Alois P. Heinz, Table of n, a(n) for n = 0..1000
- Nicolas Bělohoubek and Antonín Slavík, L-Tetromino Tilings and Two-Color Integer Compositions, Univ. Karlova (Czechia, 2025). See p. 10.
- Index entries for linear recurrences with constant coefficients, signature (0,5,6,4,0,-1,0,-3,-2,-4,0,-2).
-
a:= n-> (Matrix(12, (i, j)-> `if`(i+1=j, 1, `if`(i=12,
[-2, 0, -4, -2, -3, 0, -1, 0, 4, 6, 5, 0][j], 0)))^(n+8).
<<-1, 0, 1/2, [0$5][], 1, 0, 3, 6>>)[1, 1]:
seq(a(n), n=0..40);
-
a[n_] := MatrixPower[ Table[ If[i+1 == j, 1, If[i == 12, {-2, 0, -4, -2, -3, 0, -1, 0, 4, 6, 5, 0}[[j]], 0]], {i, 1, 12}, {j, 1, 12}], n+8].{-1, 0, 1/2, 0, 0, 0, 0, 0, 1, 0, 3, 6} // First; Table[a[n], {n, 0, 40}] (* Jean-François Alcover, Dec 05 2013, after Maple *)
A054855
Number of ways to tile a 5 X n area with 1 X 1 and 2 X 2 tiles.
Original entry on oeis.org
1, 1, 8, 21, 93, 314, 1213, 4375, 16334, 59925, 221799, 817280, 3018301, 11134189, 41096528, 151643937, 559640289, 2065192514, 7621289593, 28124714395, 103789150046, 383013144129, 1413437041011, 5216013647648, 19248692843977
Offset: 0
Silvia Heubach (silvi(AT)cine.net), Apr 21 2000
a(2)=8 as there is one tiling of a 5 X 2 area with only 1 X 1 tiles, 4 tilings with exactly one 2 X 2 tile and 3 tilings with exactly two 2 X 2 tiles.
-
f[{A_, B_}] := Module[{til = A, basic = B}, {Flatten[Append[til, ListConvolve[A, B]]], AppendTo[basic, 2 Fibonacci[Length[B] + 2]]}]; NumOfTilings[n_] := Nest[f, {{1, 1}, {1, 7}}, n - 2][[1]] NumOfTilings[30]
A063650
Number of ways to tile a 6 X n rectangle with 1 X 1 and 2 X 2 tiles.
Original entry on oeis.org
1, 1, 13, 43, 269, 1213, 6427, 31387, 159651, 795611, 4005785, 20064827, 100764343, 505375405, 2536323145, 12724855013, 63851706457, 320373303983, 1607526474153, 8065864257905, 40471399479495, 203068825478591, 1018918472214687, 5112520236292975, 25652573037707685
Offset: 0
-
I:=[1,1,13,43,269,1213]; [n le 6 select I[n] else 2*Self(n-1)+16*Self(n-2)+Self(n-3)-27*Self(n-4)+Self(n-5)+4*Self(n-6): n in [1..30]]; // Vincenzo Librandi, Oct 30 2018
-
LinearRecurrence[{2, 16, 1, -27, 1, 4}, {1, 1, 13, 43, 269, 1213}, 22] (* Jean-François Alcover, Oct 30 2018 *)
CoefficientList[Series[(-1+x+5*x^2-x^4)/(-1+2*x+16*x^2+x^3-27*x^4+x^5+4*x^6), {x, 0, 50}], x] (* Stefano Spezia, Oct 30 2018 *)
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
a(2) = 11, because there are 11 tilings of a 4 X 2 rectangle using dominoes and right trominoes:
.___. .___. .___. ._._. ._._. .___. .___. .___. .___. .___. .___.
|___| |___| |_._| | | | | | | |___| |___| | ._| |_. | | ._| |_. |
|___| |_._| | | | |_|_| |_|_| | ._| |_. | |_| | | |_| |_| | | |_|
|___| | | | |_|_| |___| | | | |_| | | |_| |___| |___| | |_| |_| |
|___| |_|_| |___| |___| |_|_| |___| |___| |___| |___| |___| |___| .
- Alois P. Heinz, Table of n, a(n) for n = 0..400
- Index entries for linear recurrences with constant coefficients, signature (4, 21, -25, -65, -17, 24, -11, -15, 9).
-
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);
-
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 *)
A063654
Number of ways to tile a 10 X n rectangle with 1 X 1 and 2 X 2 tiles.
Original entry on oeis.org
1, 1, 89, 683, 16717, 221799, 4005785, 61643709, 1029574631, 16484061769, 269718819131, 4364059061933, 71019435701025, 1152314664726905, 18725412666911121, 304052089851133193, 4939032362569285343
Offset: 0
- Index entries for linear recurrences with constant coefficients, signature (11, 195, -1459, -10427, 79002, 188873, -1922453, -522744, 21726132, -11085988, -137059276, 114023550, 533938164, -503739499, -1345858084, 1272444796, 2223076291, -1997887777, -2382027317, 2015253425, 1613022647, -1309632545, -660948344, 533727589, 152685069, -128889883, -17772195, 16954690, 883980, -1089264, -11392, 26112).
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
a(4) = 6, because there are 6 tilings of a 4 X 4 rectangle using right trominoes and 2 X 2 tiles:
.___.___. .___.___. .___.___. .___.___. .___.___. .___.___.
| . | . | | ._|_. | | ._| . | | ._|_. | | ._|_. | | . |_. |
|___|___| |_| . |_| |_| |___| |_| ._|_| |_|_. |_| |___| |_|
| . | . | | |___| | | |___| | | |_| . | | . |_| | | |___| |
|___|___| |___|___| |___|___| |___|___| |___|___| |___|___|
- Alois P. Heinz, Table of n, a(n) for n = 0..1000
- Index entries for linear recurrences with constant coefficients, signature (1,1,9,1,-3,-22,-16,0,-4).
-
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);
-
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 *)
A063652
Number of ways to tile an 8 X n rectangle with 1 X 1 and 2 X 2 tiles.
Original entry on oeis.org
1, 1, 34, 171, 2115, 16334, 159651, 1382259, 12727570, 113555791, 1029574631, 9258357134, 83605623809, 753361554685, 6795928721858, 61270295494859, 552555688390363, 4982395765808506, 44929655655496287, 405145692220245539, 3653405881837027898
Offset: 0
- S. Butler and S. Osborne, Counting tilings by taking walks, 2012. - From _N. J. A. Sloane_, Dec 27 2012
- R. J. Mathar, Tiling nXm rectangles with 1X1 and sXs squares, arXiv:1609.03964 (2016) Section 4.1
- Index entries for linear recurrences with constant coefficients, signature (6, 50, -171, -514, 1800, 845, -5430, 704, 6175, -1762, -2810, 870, 392, -120).
A063653
Number of ways to tile a 9 X n rectangle with 1 X 1 and 2 X 2 tiles.
Original entry on oeis.org
1, 1, 55, 341, 5933, 59925, 795611, 9167119, 113555791, 1355115601, 16484061769, 198549329897, 2403674442213, 29023432116879, 350917980468767, 4239961392742933, 51247532773412135, 619304595300705203, 7484739788762129061, 90454037365096154821
Offset: 0
- Index entries for linear recurrences with constant coefficients, signature (6, 110, -262, -2786, 5916, 25168, -53907, -95299, 197820, 193866, -340168, -228528, 279636, 137864, -108909, -33736, 20214, 2460, -1296).
Subscripts in formula repaired by
Ron Hardin, Dec 29 2010
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