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 1-10 of 10 results.

A226444 Number A(n,k) of tilings of a k X n rectangle using 1 X 1 squares and L-tiles; 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, 6, 5, 1, 1, 1, 1, 8, 13, 13, 8, 1, 1, 1, 1, 13, 28, 42, 28, 13, 1, 1, 1, 1, 21, 60, 126, 126, 60, 21, 1, 1, 1, 1, 34, 129, 387, 524, 387, 129, 34, 1, 1, 1, 1, 55, 277, 1180, 2229, 2229, 1180, 277, 55, 1, 1
Offset: 0

Views

Author

Alois P. Heinz, Jun 06 2013

Keywords

Comments

An L-tile is a 2 X 2 square with the upper right 1 X 1 subsquare removed and no rotations are allowed.

Examples

			A(3,3) = 6:
  ._____.  ._____.  ._____.  ._____.  ._____.  ._____.
  |_|_|_|  | |_|_|  |_|_|_|  |_| |_|  |_|_|_|  |_| |_|
  |_|_|_|  |___|_|  | |_|_|  |_|___|  |_| |_|  | |___|
  |_|_|_|  |_|_|_|  |___|_|  |_|_|_|  |_|___|  |___|_|.
Square array A(n,k) begins:
  1, 1,  1,   1,    1,     1,      1,       1,        1, ...
  1, 1,  1,   1,    1,     1,      1,       1,        1, ...
  1, 1,  2,   3,    5,     8,     13,      21,       34, ...
  1, 1,  3,   6,   13,    28,     60,     129,      277, ...
  1, 1,  5,  13,   42,   126,    387,    1180,     3606, ...
  1, 1,  8,  28,  126,   524,   2229,    9425,    39905, ...
  1, 1, 13,  60,  387,  2229,  13322,   78661,   466288, ...
  1, 1, 21, 129, 1180,  9425,  78661,  647252,  5350080, ...
  1, 1, 34, 277, 3606, 39905, 466288, 5350080, 61758332, ...
		

Crossrefs

Columns (or rows) k=0+1,2-10 give: A000012, A000045(n+1), A002478, A105262, A219737(n-1) for n>2, A219738 (n-1) for n>2, A219739(n-1) for n>1, A219740(n-1) for n>2, A226543, A226544.
Main diagonal gives A066864(n-1).
See A219741 for an array with very similar entries. - N. J. A. Sloane, Aug 22 2013
Cf. A322494.

Programs

  • Maple
    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; b(n, subsop(k=1, l))+
            `if`(k b(max(n, k), [0$min(n, k)]):
    seq(seq(A(n, d-n), n=0..d), d=0..14);
    [Zeilberger gives Maple code to find generating functions for the columns - see links in A228285. - N. J. A. Sloane, Aug 22 2013]
  • Mathematica
    b[n_, l_] := b[n, l] = Module[{k, t}, Which[Max[l] > n, 0, n == 0 || l == {}, 1, Min[l] > 0, t = Min[l]; b[n-t, l-t], True, k = Position[l, 0, 1][[1, 1]]; b[n, ReplacePart[l, k -> 1]] + If[k < Length[l] && l[[k+1]] == 0, b[n, ReplacePart[l, {k -> 1, k+1 -> 2}]], 0] ] ]; a[n_, k_] := b[Max[n, k], Array[0&, Min[n, k]]]; Table[Table[a[n, d-n], {n, 0, d}], {d, 0, 14}] // Flatten (* Jean-François Alcover, Dec 18 2013, translated from Maple *)

Formula

The k-th column satisfies a recurrence of order Fibonacci(k+1) [Zeilberger] - see links in A228285. - N. J. A. Sloane, Aug 22 2013

A322496 Number of tilings of a 3 X n rectangle using V (2m+1)-ominoes (m >= 0) in standard orientation.

Original entry on oeis.org

1, 1, 3, 8, 18, 44, 107, 257, 621, 1500, 3620, 8740, 21101, 50941, 122983, 296908, 716798, 1730504, 4177807, 10086117, 24350041, 58786200, 141922440, 342631080, 827184601, 1997000281, 4821185163, 11639370608, 28099926378, 67839223364, 163778373107
Offset: 0

Views

Author

Alois P. Heinz, Dec 12 2018

Keywords

Comments

The shapes of the tiles are:
._.
._. | |
.. | |. | |..
|| |__| |___| .

Examples

			a(3) = 8:
  ._____.  ._____.  ._____.  ._____.  ._____.  ._____.  ._____.  ._____.
  |_|_|_|  | |_|_|  |_|_|_|  |_| |_|  |_|_|_|  |_| |_|  | |_|_|  | | |_|
  |_|_|_|  |___|_|  | |_|_|  |_|___|  |_| |_|  | |___|  | |_|_|  | |___|
  |_|_|_|  |_|_|_|  |___|_|  |_|_|_|  |_|___|  |___|_|  |_____|  |_____|  .
		

Crossrefs

Column k=3 of A322494.

Programs

  • Maple
    a:= n-> (<<0|1|0|0>, <0|0|1|0>, <0|0|0|1>, <1|3|2|1>>^n)[4$2]:
    seq(a(n), n=0..40);

Formula

G.f.: -1/((x^2+x+1)*(x^2+2*x-1)).
a(n) = 2*a(n-1) + a(n-2) + A049347(n). - Greg Dresden, May 18 2020

A322497 Number of tilings of a 4 X n rectangle using V (2m+1)-ominoes (m >= 0) in standard orientation.

Original entry on oeis.org

1, 1, 5, 18, 68, 233, 838, 2989, 10687, 38097, 136002, 485370, 1732377, 6182628, 22065919, 78752901, 281068809, 1003130814, 3580164896, 12777572157, 45603031014, 162756761629, 580877276331, 2073145244569, 7399034871398, 26407082201462, 94246615039341
Offset: 0

Views

Author

Alois P. Heinz, Dec 12 2018

Keywords

Comments

The shapes of the tiles are:
._.
._. | |
._. | | | |
.. | |. | |.. | |.._.
|| |__| |___| |_____| .

Crossrefs

Column k=4 of A322494.

Programs

  • Mathematica
    LinearRecurrence[{1,5,9,17,13,5,-2,-2},{1,1,5,18,68,233,838,2989},30] (* Harvey P. Dale, May 02 2022 *)

Formula

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

A322498 Number of tilings of a 5 X n rectangle using V (2m+1)-ominoes (m >= 0) in standard orientation.

Original entry on oeis.org

1, 1, 8, 44, 233, 1262, 6523, 34468, 181615, 957006, 5044388, 26575335, 140039124, 737911089, 3888300180, 20488828781, 107962314409, 568889946804, 2997672175041, 15795742092745, 83233076938962, 438583048406589, 2311041500385152, 12177654397383350
Offset: 0

Views

Author

Alois P. Heinz, Dec 12 2018

Keywords

Comments

The shapes of the tiles are:
._.
._. | |
._. | | | |
.. | |. | |.. | |.._.
|| |__| |___| |_____| ... .

Crossrefs

Column k=5 of A322494.

Formula

G.f.: (2*x^11 -8*x^10 +4*x^9 -7*x^8 -18*x^7 -29*x^6 -32*x^5 -20*x^4 -10*x^3 -3*x^2+1) / (10*x^16 -50*x^15 +76*x^14 -57*x^13 -58*x^12 -58*x^11 -324*x^10 -361*x^9 -576*x^8 -551*x^7 -392*x^6 -240*x^5 -93*x^4 -36*x^3 -10*x^2 -x+1).

A322499 Number of tilings of a 6 X n rectangle using V (2m+1)-ominoes (m >= 0) in standard orientation.

Original entry on oeis.org

1, 1, 13, 107, 838, 6523, 51420, 396500, 3086898, 24009733, 186735416, 1452320952, 11295996925, 87852065113, 683271518863, 5314139902766, 41330688551925, 321449136734050, 2500069029481412, 19444268928224485, 151227677898412290, 1176172285095334802
Offset: 0

Views

Author

Alois P. Heinz, Dec 12 2018

Keywords

Comments

The shapes of the tiles are:
._.
._. | |
._. | | | |
.. | |. | |.. | |.._.
|| |__| |___| |_____| ... .

Crossrefs

Column k=6 of A322494.

A322500 Number of tilings of a 7 X n rectangle using V (2m+1)-ominoes (m >= 0) in standard orientation.

Original entry on oeis.org

1, 1, 21, 257, 2989, 34468, 396500, 4577274, 52338705, 600923375, 6897569624, 79170705722, 908721438900, 10430285080567, 119719520002653, 1374133015203548, 15772280213569812, 181033948036338279, 2077904397828614231, 23850149155575310594, 273751580233289217307
Offset: 0

Views

Author

Alois P. Heinz, Dec 12 2018

Keywords

Comments

The shapes of the tiles are:
._.
._. | |
._. | | | |
.. | |. | |.. | |.._.
|| |__| |___| |_____| ... .

Crossrefs

Column k=7 of A322494.

A322501 Number of tilings of an 8 X n rectangle using V (2m+1)-ominoes (m >= 0) in standard orientation.

Original entry on oeis.org

1, 1, 34, 621, 10687, 181615, 3086898, 52338705, 888837716, 15029968375, 254605651987, 4312608660046, 73048456842772, 1237312902210617, 20957926357019583, 354990566329457044, 6012925190578975735, 101848368521145389471, 1725133116479186659346
Offset: 0

Views

Author

Alois P. Heinz, Dec 12 2018

Keywords

Comments

The shapes of the tiles are:
._.
._. | |
._. | | | |
.. | |. | |.. | |.._.
|| |__| |___| |_____| ... .

Crossrefs

Column k=8 of A322494.

A322502 Number of tilings of a 9 X n rectangle using V (2m+1)-ominoes (m >= 0) in standard orientation.

Original entry on oeis.org

1, 1, 55, 1500, 38097, 957006, 24009733, 600923375, 15029968375, 376116199534, 9394097589045, 234816663728554, 5869407851857410, 146709570371173411, 3667093829512515427, 91661210468678400305, 2291126428942263984999, 57268064504720859650768
Offset: 0

Views

Author

Alois P. Heinz, Dec 12 2018

Keywords

Comments

The shapes of the tiles are:
._.
._. | |
._. | | | |
.. | |. | |.. | |.._.
|| |__| |___| |_____| ... .

Crossrefs

Column k=9 of A322494.

A322503 Number of tilings of a 10 X n rectangle using V (2m+1)-ominoes (m >= 0) in standard orientation.

Original entry on oeis.org

1, 1, 89, 3620, 136002, 5044388, 186735416, 6897569624, 254605651987, 9394097589045, 346688563051200, 12783317143959681, 471522273648618022, 17392356171712222007, 641526227823336378247, 23663017416745429407437, 872822255075124794048661
Offset: 0

Views

Author

Alois P. Heinz, Dec 12 2018

Keywords

Comments

The shapes of the tiles are:
._.
._. | |
._. | | | |
.. | |. | |.. | |.._.
|| |__| |___| |_____| ... .

Crossrefs

Column k=10 of A322494.

A322495 Number of tilings of an n X n square using V (2m+1)-ominoes (m >= 0) in standard orientation.

Original entry on oeis.org

1, 1, 2, 8, 68, 1262, 51420, 4577274, 888837716, 376116199534, 346688563051200, 695975307003529228
Offset: 0

Views

Author

Alois P. Heinz, Dec 12 2018

Keywords

Comments

The shapes of the tiles are:
._.
._. | |
._. | | | |
.. | |. | |.. | |.._.
|| |__| |___| |_____| ... .

Examples

			a(3) = 8:
  ._____.  ._____.  ._____.  ._____.  ._____.  ._____.  ._____.  ._____.
  |_|_|_|  | |_|_|  |_|_|_|  |_| |_|  |_|_|_|  |_| |_|  | |_|_|  | | |_|
  |_|_|_|  |___|_|  | |_|_|  |_|___|  |_| |_|  | |___|  | |_|_|  | |___|
  |_|_|_|  |_|_|_|  |___|_|  |_|_|_|  |_|___|  |___|_|  |_____|  |_____|.
.
		

Crossrefs

Main diagonal of A322494.

Programs

  • Maple
    b:= proc(n, l) option remember; local k, m, r;
          if n=0 or l=[] then 1
        elif min(l)>0 then (t-> b(n-t, map(h->h-t, l)))(min(l))
        elif l[-1]=n then b(n, subsop(-1=[][], l))
        else for k while l[k]>0 do od; r:= 0;
             for m from 0 while k+m<=nops(l) and l[k+m]=0 and n>m do
               r:= r+b(n, [l[1..k-1][], 1$m, m+1, l[k+m+1..nops(l)][]])
             od; r
          fi
        end:
    a:= n-> b(n, [0$n]):
    seq(a(n), n=0..9);
  • Mathematica
    b[n_, l_] := b[n, l] = Module[{k, m, r}, Which[n == 0 || l == {}, 1, Min[l] > 0, Function[t, b[n-t, l-t]][Min[l]], l[[-1]] == n, b[n, ReplacePart[l, -1 -> Nothing]], True, For[k = 1, l[[k]] > 0, k++]; r = 0; For[m = 0, k + m <= Length[l] && l[[k+m]] == 0 && n > m, m++, r = r + b[n, Join[l[[1 ;; k-1]], Array[1&, m], {m+1}, l[[k+m+1 ;; Length[l]]]]]]; r]];
    a[n_] := b[n, Array[0&, n]];
    a /@ Range[0, 9] (* Jean-François Alcover, Apr 22 2021, after Alois P. Heinz *)
Showing 1-10 of 10 results.