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.

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A352589 Triangle read by rows: T(n,k) = number of tilings of a n X k rectangle using 2 X 2 and 1 X 1 tiles and dominoes, n >= 0, k = 0..n.

Original entry on oeis.org

1, 1, 1, 1, 2, 8, 1, 3, 26, 163, 1, 5, 90, 1125, 15623, 1, 8, 306, 7546, 210690, 5684228, 1, 13, 1046, 51055, 2865581, 154869092, 8459468955, 1, 21, 3570, 344525, 38879777, 4207660108, 460706560545, 50280716999785, 1, 34, 12190, 2326760, 527889422, 114411435032, 25111681648122, 5492577770367562, 1202536689448371122
Offset: 0

Views

Author

Gerhard Kirchner, Mar 22 2022

Keywords

Comments

For the tiling algorithm, see A351322.
Reading the sequence {T(n,k)} for k>n, use T(k,n) instead of T(n,k).

Examples

			Triangle T(n,k) begins
  n\k_0__1____2______3________4__________5___________6
  0:  1
  1:  1  1
  2:  1  2    8
  3:  1  3   26    163
  4:  1  5   90   1125    15623
  5:  1  8  306   7546   210690    5684228
  6:  1 13 1046  51055  2865581  154869092  8459468955
		

Crossrefs

Row/columns 0..5 are A000012, A000045(n+1), A052543, A226351, A352590, A352591.
Main diagonal is A353777.
Cf. A351322.

Programs

  • Maple
    b:= proc(n, l) option remember; local k, t;
          if 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 while l[k]>0 do od; b(n, subsop(k=1, l))+
             `if`(n>1, b(n, subsop(k=2, l)), 0)+ `if`(k1, b(n, subsop(k=2, k+1=2, l)), 0), 0)
          fi
        end:
    T:= (n, k)-> b(max(n, k), [0$min(n, k)]):
    seq(seq(T(n, k), k=0..n), n=0..10);  # Alois P. Heinz, May 06 2022
  • Mathematica
    b[n_, l_List] := b[n, l] = Module[{k, t}, Which[
         n == 0 || l == {}, 1,
         Min[l] > 0, t = Min[l]; b[n - t, l - t],
         True, For[k = 1, l[[k]] > 0, k++]; b[n, ReplacePart[l, k -> 1]] +
               If[n > 1, b[n, ReplacePart[l, k -> 2]], 0] + If[k < Length[l] &&
               l[[k + 1]] == 0, b[n, ReplacePart[l, {k -> 1, k + 1 -> 1}]] +
               If[n > 1, b[n, ReplacePart[l, {k -> 2, k+1 -> 2}]], 0], 0]]];
    T[n_, k_] := b[Max[n, k], Array[0&, Min[n, k]]];
    Table[Table[T[n, k], {k, 0, n}], {n, 0, 10}] // Flatten (* Jean-François Alcover, May 16 2022, after Alois P. Heinz *)
  • Maxima
    /* See Maxima code link. */

A353934 Number of tilings of an n X n square using right trominoes, dominoes, and monominoes.

Original entry on oeis.org

1, 1, 11, 369, 83374, 90916452, 546063639624, 17259079054003609, 2916019543694306398589, 2620143594924539083433405392, 12541344781693990981151732534871036, 319608708168951734031266758322647453517098, 43373075269161087186367095378869660507262626652634
Offset: 0

Views

Author

Alois P. Heinz, May 11 2022

Keywords

Examples

			a(2) = 11:
  .___. .___. .___. .___. .___. .___. .___. .___. .___. .___. .___.
  |_|_| |___| | | | |_|_| |___| |_| | | |_| |_| | |_. | | ._| | |_|
  |_|_| |___| |_|_| |___| |_|_| |_|_| |_|_| |___| |_|_| |_|_| |___| .
		

Crossrefs

Formula

a(n) = A353877(n,n).
Showing 1-2 of 2 results.