A165799 -id:A165799 - cp's OEIS frontend

A219946 Number A(n,k) of tilings of a k X n rectangle using right trominoes and 2 X 2 tiles; square array A(n,k), n>=0, k>=0, read by antidiagonals.

1, 1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 1, 1, 0, 2, 2, 0, 1, 1, 0, 1, 0, 1, 0, 1, 1, 0, 4, 4, 4, 4, 0, 1, 1, 0, 5, 0, 6, 0, 5, 0, 1, 1, 0, 6, 8, 16, 16, 8, 6, 0, 1, 1, 0, 13, 0, 37, 0, 37, 0, 13, 0, 1, 1, 0, 16, 16, 92, 136, 136, 92, 16, 16, 0, 1, 1, 0, 25, 0, 245, 0, 545, 0, 245, 0, 25, 0, 1

Offset: 0

Alois P. Heinz, Dec 01 2012

			A(4,4) = 6, because there are 6 tilings of a 4 X 4 rectangle using right trominoes and 2 X 2 tiles:
  .___.___. .___.___. .___.___. .___.___. .___.___. .___.___.
  | . | . | | ._|_. | | ._| . | | ._|_. | | ._|_. | | . |_. |
  |___|___| |_| . |_| |_| |___| |_| ._|_| |_|_. |_| |___| |_|
  | . | . | | |___| | | |___| | | |_| . | | . |_| | | |___| |
  |___|___| |___|___| |___|___| |___|___| |___|___| |___|___|
Square array A(n,k) begins:
  1,  1,  1,  1,   1,    1,     1,      1,       1,        1, ...
  1,  0,  0,  0,   0,    0,     0,      0,       0,        0, ...
  1,  0,  1,  2,   1,    4,     5,      6,      13,       16, ...
  1,  0,  2,  0,   4,    0,     8,      0,      16,        0, ...
  1,  0,  1,  4,   6,   16,    37,     92,     245,      560, ...
  1,  0,  4,  0,  16,    0,   136,      0,    1128,      384, ...
  1,  0,  5,  8,  37,  136,   545,   2376,   10534,    46824, ...
  1,  0,  6,  0,  92,    0,  2376,   5504,   71248,   253952, ...
  1,  0, 13, 16, 245, 1128, 10534,  71248,  652036,  5141408, ...
  1,  0, 16,  0, 560,  384, 46824, 253952, 5141408, 44013568, ...

Alois P. Heinz, Antidiagonals n = 0..35, flattened
Kai Liang, Solving tiling enumeration problems by tensor network contractions, arXiv:2503.17698 [math.CO], 2025. See p. 25, Table 4.
Wikipedia, Tromino

Columns (or rows) k=0-10 give: A000012, A000007, A052947, A077957, A165799, A190759, A219947, A219948, A219949, A219950, A219951.

Main diagonal gives: A219952.

b:= proc(n, l) option remember; local k, t;
      if max(l[])>n then 0 elif n=0 or l=[] then 1
    elif min(l[])>0 then t:=min(l[]); b(n-t, map(h->h-t, l))
    else for k do if l[k]=0 then break fi od;
         `if`(k>1 and l[k-1]=1, b(n, subsop(k=2, k-1=2, l)), 0)+
         `if`(k `if`(n>=k, b(n, [0$k]), b(k, [0$n])):
seq(seq(A(n, d-n), n=0..d), d=0..14);

b[n_, l_] := b[n, l] = Module[{k, t}, If[Max[l] > n , 0 , If [n == 0 || l == {},1 , If[Min[l] > 0, t = Min[l]; b[n-t, l-t], For[k = 1, k <= Length[l], k++, If[l[[k]] == 0 , Break[]]]; If[k > 1 && l[[k-1]] == 1, b[n, ReplacePart[l, {k -> 2, k-1 -> 2}]], 0] + If[k < Length[l] && l[[k+1]] == 1, b[n, ReplacePart[l, {k -> 2, k+1 -> 2}]], 0] + If[k < Length[l] && l[[k+1]] == 0, b[n, ReplacePart[l, {k -> 2, k+1 -> 2}]] + b[n, ReplacePart[l, {k -> 1, k+1 -> 2}]] + b[n, ReplacePart[l, {k -> 2, k+1 -> 1}]], 0]+If[k+1 < Length[l] && l[[k+1]] == 0 && l[[k+2]] == 0, b[n, ReplacePart[l, {k -> 2, k+1 -> 2, k+2 -> 2}]], 0]]]]]; a[n_, ] := If[n >= k, b[n, Array[0&, k]], b[k, Array[0&, n]]]; Table[Table[a[n, d-n], {n, 0, d}], {d, 0, 14}] // Flatten (* _Jean-François Alcover, Nov 26 2013, translated from Alois P. Heinz's Maple program *)

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

Alois P. Heinz, Jun 03 2013

			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).

Cf. A054854, A054856, A084480, A165716, A165791, A165799, A174248, A232497, A233191, A233266.

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 *)

G.f.: (x^6+2*x^2-1) / (-2*x^12 -4*x^10 -2*x^9 -3*x^8 -x^6 +4*x^4 +6*x^3 +5*x^2-1).

A190759 Number of tilings of a 5 X n rectangle using right trominoes and 2 X 2 tiles.

Original entry on oeis.org

1, 0, 4, 0, 16, 0, 136, 0, 1128, 384, 8120, 6912, 60904, 75136, 491960, 720640, 4023592, 6828928, 32819320, 63472640, 270471784, 574543744, 2256221368, 5119155712, 18940876712, 45266369152, 159625747960, 397949457408, 1350573713256

Offset: 0

Alois P. Heinz, May 18 2011

			a(2) = 4, because there are 4 tilings of a 5 X 2 rectangle using right trominoes and 2 X 2 tiles:
.___. .___. .___. .___.
| . | | . | | ._| |_. |
|___| |___| |_| | | |_|
| ._| |_. | |___| |___|
|_| | | |_| | . | | . |
|___| |___| |___| |___|

Alois P. Heinz, Table of n, a(n) for n = 0..650
Index entries for linear recurrences with constant coefficients, signature (0, 13, 2, -57, -12, 190, -10, -453, 396, -2, -88, 308, -160, -80).

Cf. A165799, A165791, A165716, A054854, A054856.

Column k=5 of A219946.

a:= n-> (Matrix(14, (i, j)-> `if`(i=j-1, 1, `if`(i=14, [-80, -160, 308, -88, -2, 396, -453, -10, 190, -12, -57, 2, 13, 0][j], 0)))^n. <<0, 1/4, 0, 1, 0, 4, 0, 16, 0, 136, 0, 1128, 384, 8120>>)[4,1]: seq(a(n), n=0..30);

a[n_] := (MatrixPower[ Table[ If[i == j-1, 1, If[i == 14, {-80, -160, 308, -88, -2, 396, -453, -10, 190, -12, -57, 2, 13, 0}[[j]], 0]], {i, 1, 14}, {j, 1, 14}], n] . {0, 1/4, 0, 1, 0, 4, 0, 16, 0, 136, 0, 1128, 384, 8120})[[4]]; Table[a[n], {n, 0, 30}] (* Jean-François Alcover, Dec 05 2013, translated from Alois P. Heinz's Maple program *)

G.f.: (20*x^12+40*x^11 +18*x^10+52*x^9 +35*x^8-26*x^7 +34*x^6-4*x^5 -21*x^4 +2*x^3 +9*x^2-1) / (-80*x^14-160*x^13 +308*x^12-88*x^11 -2*x^10+396*x^9 -453*x^8-10*x^7 +190*x^6-12*x^5 -57*x^4+2*x^3 +13*x^2-1).

A219862 Number of tilings of a 4 X n rectangle using dominoes and straight (3 X 1) trominoes.

Original entry on oeis.org

1, 1, 7, 41, 184, 1069, 5624, 29907, 161800, 862953, 4631107, 24832532, 133028028, 713283085, 3822965706, 20491221900, 109840081931, 588746006676, 3155783700063, 16915482096570, 90669231898345, 486001022349368, 2605035346917456, 13963368769216664

Offset: 0

Alois P. Heinz, Nov 29 2012

			a(2) = 7, because there are 7 tilings of a 4 X 2 rectangle using dominoes and straight (3 X 1) trominoes:
.___.   .___.   .___.   .___.   .___.   .___.   .___.
| | |   |___|   |___|   | | |   |___|   |___|   | | |
| | |   | | |   |___|   |_|_|   | | |   |___|   |_|_|
|_|_|   | | |   |___|   |___|   |_|_|   | | |   | | |
|___|   |_|_|   |___|   |___|   |___|   |_|_|   |_|_|

Alois P. Heinz, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (4, 6, 27, -102, 17, -395, 797, -644, 2838, -2657, 2523, -8602, 4310, -8873, 16066, -2769, 18628, -15477, 3863, -27627, 5040, -9300, 19846, 1875, 15731, -6435, 1924, -7786, -680, -4783, 1842, -657, 1108, 32, 734, -278, 88, -32, 10, -58, 13, -3, -1, 0, 1).

Cf. A165716, A165791, A165799, A190759, A202536.

Column k=4 of A219866.

gf:= -(x^42 +x^41 -4*x^40 +4*x^38 -41*x^37 +16*x^36 +45*x^35 +67*x^34 -166*x^33 +282*x^32 -148*x^31 +155*x^30 -405*x^29 +995*x^28 -1118*x^27 +575*x^26 -1863*x^25 +402*x^24 -3552*x^23 +2577*x^22 -406*x^21 +5797*x^20 -741*x^19 +3045*x^18 -5606*x^17 +223*x^16 -4294*x^15 +2924*x^14 -753*x^13 +3011*x^12 -1029*x^11 +811*x^10 -1205*x^9 +248*x^8 -310*x^7 +229*x^6 -17*x^5 +53*x^4 -20*x^3 -3*x^2 -3*x +1) /
(x^45 -x^43 -3*x^42 +13*x^41 -58*x^40 +10*x^39 -32*x^38 +88*x^37 -278*x^36 +734*x^35 +32*x^34 +1108*x^33 -657*x^32 +1842*x^31 -4783*x^30 -680*x^29 -7786*x^28 +1924*x^27 -6435*x^26 +15731*x^25 +1875*x^24 +19846*x^23 -9300*x^22 +5040*x^21 -27627*x^20 +3863*x^19 -15477*x^18 +18628*x^17 -2769*x^16 +16066*x^15 -8873*x^14 +4310*x^13 -8602*x^12 +2523*x^11 -2657*x^10 +2838*x^9 -644*x^8 +797*x^7 -395*x^6 +17*x^5 -102*x^4 +27*x^3 +6*x^2 +4*x -1):
a:= n-> coeff(series(gf, x, n+1), x, n):
seq(a(n), n=0..30);

G.f.: see Maple program.

A202536 Number of tilings of a 4 X n rectangle using straight (3 X 1) trominoes and 2 X 2 tiles.

Original entry on oeis.org

1, 0, 1, 3, 3, 8, 21, 31, 70, 165, 286, 615, 1351, 2548, 5353, 11343, 22320, 46349, 96516, 193944, 400313, 826747, 1678540, 3453642, 7105102, 14498569, 29781633, 61158957, 125108639, 256763850, 526846289, 1079030715, 2213527089, 4540131569, 9304062828

Offset: 0

Alois P. Heinz, Dec 20 2011

			a(3) = 3, because there are 3 tilings of a 4 X 3 rectangle using straight (3 X 1) trominoes and 2 X 2 tiles:
._____.  ._____.  ._._._.
| | | |  |_____|  |_____|
| | | |  | | | |  |_____|
|_|_|_|  | | | |  |_____|
|_____|  |_|_|_|  |_____|
a(4) = 3, because there are 3 tilings of a 4 X 4 rectangle using straight (3 X 1) 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, 11, -9, -8, -48, 29, 23, 115, -44, -31, -173, 35, 19, 174, -18, 2, -119, 10, -14, 56, -8, 12, -19, 4, -5, 5, -1, 1, -1).

Cf. A165716, A165791, A165799, A190759, A219862.

Column k=4 of A219967.

gf:= -(x^3+x-1) *(x^18 -3*x^15 +x^14 +7*x^12 -3*x^11 -11*x^9 +3*x^8 +12*x^6 -x^5 -6*x^3+1) *(x-1)^2 *(x^2+x+1)^2 / (x^30 -x^29 +x^28 -5*x^27 +5*x^26 -4*x^25 +19*x^24 -12*x^23 +8*x^22 -56*x^21 +14*x^20 -10*x^19 +119*x^18 -2*x^17 +18*x^16 -174*x^15 -19*x^14 -35*x^13 +173*x^12 +31*x^11 +44*x^10 -115*x^9 -23*x^8 -29*x^7 +48*x^6 +8*x^5 +9*x^4 -11*x^3 -x^2 -x+1):
a:= n-> coeff(series(gf, x, n+1),x,n);
seq(a(n), n=0..50);

G.f.: see Maple program.

cp's OEIS Frontend

A219946 Number A(n,k) of tilings of a k X n rectangle using right trominoes and 2 X 2 tiles; square array A(n,k), n>=0, k>=0, read by antidiagonals.

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A226322 Number of tilings of a 4 X n rectangle using L tetrominoes and 2 X 2 tiles.

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A190759 Number of tilings of a 5 X n rectangle using right trominoes and 2 X 2 tiles.

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A219862 Number of tilings of a 4 X n rectangle using dominoes and straight (3 X 1) trominoes.

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A202536 Number of tilings of a 4 X n rectangle using straight (3 X 1) trominoes and 2 X 2 tiles.

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