A226550 -id:A226550 - cp's OEIS frontend

A226545 Number A(n,k) of squares in all tilings of a k X n rectangle using integer-sided square tiles; square array A(n,k), n>=0, k>=0, read by antidiagonals.

0, 0, 0, 0, 1, 0, 0, 2, 2, 0, 0, 3, 5, 3, 0, 0, 4, 12, 12, 4, 0, 0, 5, 25, 34, 25, 5, 0, 0, 6, 50, 98, 98, 50, 6, 0, 0, 7, 96, 256, 386, 256, 96, 7, 0, 0, 8, 180, 654, 1402, 1402, 654, 180, 8, 0, 0, 9, 331, 1625, 4938, 6940, 4938, 1625, 331, 9, 0

Offset: 0

Alois P. Heinz, Jun 10 2013

			A(3,3) = 1 + 6 + 6 + 6 + 6 + 9 = 34:
  ._____.  ._____.  ._____.  ._____.  ._____.  ._____.
  |     |  |   |_|  |_|   |  |_|_|_|  |_|_|_|  |_|_|_|
  |     |  |___|_|  |_|___|  |_|   |  |   |_|  |_|_|_|
  |_____|  |_|_|_|  |_|_|_|  |_|___|  |___|_|  |_|_|_|
Square array A(n,k) begins:
  0, 0,   0,    0,     0,      0,       0,        0, ...
  0, 1,   2,    3,     4,      5,       6,        7, ...
  0, 2,   5,   12,    25,     50,      96,      180, ...
  0, 3,  12,   34,    98,    256,     654,     1625, ...
  0, 4,  25,   98,   386,   1402,    4938,    16936, ...
  0, 5,  50,  256,  1402,   6940,   33502,   157279, ...
  0, 6,  96,  654,  4938,  33502,  221672,  1426734, ...
  0, 7, 180, 1625, 16936, 157279, 1426734, 12582472, ...

Alois P. Heinz, Antidiagonals n = 0..30, flattened

Columns (or rows) k=0-10 give: A000004, A001477, A067331(n-1) for n>0, A226546, A226547, A226548, A226549, A226550, A226551, A226552, A226553.
Main diagonal gives A226554.
Cf. A113881, A219924.

b:= proc(n, l) option remember; local i, k, s, t;
      if max(l[])>n then [0,0] elif n=0 or l=[] then [1,0]
    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; s:=[0$2];
         for i from k to nops(l) while l[i]=0 do s:=s+(h->h+[0, h[1]])
           (b(n, [l[j]$j=1..k-1, 1+i-k$j=k..i, l[j]$j=i+1..nops(l)]))
         od; s
      fi
    end:
A:= (n, k)-> `if`(n>=k, b(n, [0$k]), b(k, [0$n]))[2]:
seq(seq(A(n, d-n), n=0..d), d=0..14);

b[n_, l_List] := b[n, l] = Module[{i, k, s, t}, Which[Max[l] > n, {0, 0}, n == 0 || l == {}, {1, 0}, Min[l] > 0, t=Min[l]; b[n-t, l-t], True, k = Position[l, 0, 1][[1, 1]]; s={0, 0}; For[i=k, i <= Length[l] && l[[i]] == 0, i++, s = s + Function[h, h+{0, h[[1]]}][b[n, Join[l[[1 ;; k-1]], Table[1+i-k, {j, k, i}], l[[i+1 ;; -1]]]]] ]; s]]; a[n_, k_] := If[n >= k, b[n, Array[0&, k]], b[k, Array[0&, n]]][[2]]; Table[Table[a[n, d-n], {n, 0, d}], {d, 0, 14}] // Flatten (* Jean-François Alcover, Dec 13 2013, translated from Maple *)

A219926 Number of tilings of a 7 X n rectangle using integer-sided square tiles.

Original entry on oeis.org

1, 1, 21, 129, 1029, 7765, 59257, 450924, 3435392, 26160354, 199243634, 1517411733, 11556549312, 88013947545, 670309228276, 5105035683160, 38879655193542, 296105186372225, 2255119850966932, 17174861374796123, 130802743517191075, 996186073044886758

Offset: 0

Alois P. Heinz, Dec 01 2012

			a(2) = 21, because there are 21 tilings of a 7 X 2 rectangle using integer-sided square tiles:
._._. .___. ._._. ._._. ._._. ._._. ._._. .___. .___. .___. .___.
|_|_| |   | |_|_| |_|_| |_|_| |_|_| |_|_| |   | |   | |   | |   |
|_|_| |___| |   | |_|_| |_|_| |_|_| |_|_| |___| |___| |___| |___|
|_|_| |_|_| |___| |   | |_|_| |_|_| |_|_| |   | |_|_| |_|_| |_|_|
|_|_| |_|_| |_|_| |___| |   | |_|_| |_|_| |___| |   | |_|_| |_|_|
|_|_| |_|_| |_|_| |_|_| |___| |   | |_|_| |_|_| |___| |   | |_|_|
|_|_| |_|_| |_|_| |_|_| |_|_| |___| |   | |_|_| |_|_| |___| |   |
|_|_| |_|_| |_|_| |_|_| |_|_| |_|_| |___| |_|_| |_|_| |_|_| |___|
._._. ._._. ._._. ._._. ._._. ._._. .___. .___. .___. ._._.
|_|_| |_|_| |_|_| |_|_| |_|_| |_|_| |   | |   | |   | |_|_|
|   | |   | |   | |_|_| |_|_| |_|_| |___| |___| |___| |   |
|___| |___| |___| |   | |   | |_|_| |   | |   | |_|_| |___|
|   | |_|_| |_|_| |___| |___| |   | |___| |___| |   | |   |
|___| |   | |_|_| |   | |_|_| |___| |   | |_|_| |___| |___|
|_|_| |___| |   | |___| |   | |   | |___| |   | |   | |   |
|_|_| |_|_| |___| |_|_| |___| |___| |_|_| |___| |___| |___|

Alois P. Heinz, Table of n, a(n) for n = 0..500

Column k=7 of A219924.

Cf. A226550.

gf:= -(6*x^18 -x^17 -9*x^16 +13*x^15 +20*x^14 -35*x^13 -47*x^12 -76*x^11 -145*x^10 -127*x^9 -8*x^8 +64*x^7 +96*x^6 +68*x^5 +7*x^4 -10*x^3 -13*x^2 -2*x +1) / (6*x^25 +11*x^24 -9*x^23 -10*x^22 +39*x^21 +12*x^20 -70*x^19 -281*x^18 -403*x^17 -110*x^16 -118*x^15 -790*x^14 -179*x^13 +466*x^12 +327*x^11 +669*x^10 +1028*x^9 +231*x^8 -45*x^7 -284*x^6 -273*x^5 -61*x^4 +45*x^3 +31*x^2 +3*x -1):
a:= n-> coeff(series(gf, x, n+1), x, n):
seq(a(n), n=0..30);

G.f.: see Maple program.

cp's OEIS Frontend

A226545 Number A(n,k) of squares in all tilings of a k X n rectangle using integer-sided square tiles; square array A(n,k), n>=0, k>=0, read by antidiagonals.

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