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 1-7 of 7 results.

A018807 Number of ways to place n^2 nonattacking kings on 2n X 2n chessboard.

Original entry on oeis.org

1, 4, 79, 3600, 281571, 32572756, 5109144543, 1027533353168, 254977173389319, 75925129079783308, 26568150968269086211, 10749154284380665611224, 4963704194366362387891227, 2588716234142991968960920692, 1511548995678989691821551648635
Offset: 0

Views

Author

Keywords

Comments

Rotations and reflections are considered distinct.
Also, number of ways to tile a (2n+1) X (2n+1) board with n^2 2 X 2 tiles and 4n+1 1 X 1 tiles, rotations and reflections counted as distinct. - David W. Wilson, Aug 18 2011
Number of maximum independent vertex sets in the 2n X 2n king graph. - Eric W. Weisstein, Jun 20 2017

Crossrefs

Formula

Asymptotic (M. Larsen, 1995): log(a(n)) = 2n*log(n) - 2n*log(2) + O(n^(4/5)*log(n)).

Extensions

a(0) added by Geoffrey H. Morley, Feb 06 2013

A350819 Array read by antidiagonals: T(m,n) is the number of maximum independent sets in the 2m X 2n king graph.

Original entry on oeis.org

1, 1, 1, 1, 4, 1, 1, 12, 12, 1, 1, 32, 79, 32, 1, 1, 80, 408, 408, 80, 1, 1, 192, 1847, 3600, 1847, 192, 1, 1, 448, 7698, 26040, 26040, 7698, 448, 1, 1, 1024, 30319, 166368, 281571, 166368, 30319, 1024, 1, 1, 2304, 114606, 976640, 2580754, 2580754, 976640, 114606, 2304, 1
Offset: 0

Views

Author

Andrew Howroyd, Jan 17 2022

Keywords

Comments

Number of ways to tile a (2m+1) X (2n+1) board with m*n 2 X 2 tiles and 2m+2n+1 1 X 1 tiles.
For m,n > 0, T(m,n) is the number of minimum dominating sets in the (3m-1) X (3n-1) king graph.

Examples

			Table begins:
=============================================
m\n | 0   1    2      3       4        5
----+----------------------------------------
  0 | 1   1    1      1       1        1 ...
  1 | 1   4   12     32      80      192 ...
  2 | 1  12   79    408    1847     7698 ...
  3 | 1  32  408   3600   26040   166368 ...
  4 | 1  80 1847  26040  281571  2580754 ...
  5 | 1 192 7698 166368 2580754 32572756 ...
  ...
		

Crossrefs

Formula

T(m,n) = T(n,m).
T(m,n) = A350818(2*m, 2*n) = A350815(3*m-1, 3*n-1).

A174154 Number of ways to place 6n nonattacking kings on a 12 x 2n chessboard.

Original entry on oeis.org

1, 448, 30319, 976640, 21137959, 357365350, 5109144543, 64737165162, 749160010737, 8080813574550, 82425144219429, 803491953235264, 7545414941610145, 68680800264413920, 608889093898882615, 5278006575696293456, 44873569636443901967, 375159494582050088590, 3090799708762482416287
Offset: 0

Views

Author

Vaclav Kotesovec, Mar 10 2010

Keywords

Crossrefs

Column k=6 of A350819.

Extensions

More terms from Jinyuan Wang, Feb 26 2020
a(0)=1 prepended by Andrew Howroyd, Mar 26 2023

A174558 Number of ways to place 8n nonattacking kings on a 16 x 2n chessboard.

Original entry on oeis.org

2304, 419933, 28432288, 1134127305, 32580145116, 749160010737, 14677177838054, 254977173389319, 4035559337688370, 59315924213143597, 821112680030028632, 10819171744710664383, 136800806311499633208, 1670597119210336446533, 19804685547188544317522, 228865023358344707514899, 2586924156960003793687130, 28681715460054576813151389, 312656761422008821513384848, 3357651442822195404605813501
Offset: 1

Views

Author

Vaclav Kotesovec, Nov 29 2010

Keywords

Crossrefs

Formula

Asymptotic formula for number of ways to place m x n nonattacking kings on a 2m x 2n chessboard (this case is m=8): f(m,n) ~ k(m)*n*(m+1)^n
First values of k(m):
k(1)=1,
k(2)=17,
k(3)=231,
k(4)=3051.17509,
k(5)=40881.99638,
k(6)=563050.92363,
k(7)=8008508.28858,
k(8)=117833087.45133
k(9)=1794306724.77472
k(10)=28276454469.76459
k(11)=461049875818.05305
k(12)=7775513990776.97046
k(13)=135589372611110.17367
k(14)=2443990803097108.58764
k(15)=45522076785406201.22572
k(16)=875939597341977670.66777
k(17)=17407856624734801679.11613
k(18)=357216046100723515478.42809
k(19)=7567101689641721175327.80272

A174155 Number of ways to place 7n nonattacking kings on a 14 x 2n chessboard.

Original entry on oeis.org

1, 1024, 114606, 5392704, 159636030, 3544192112, 64737165162, 1027533353168, 14677177838054, 193194265398240, 2383116363555182, 27889602664055396, 312546900470579954, 3378090945290324892, 35412239480510055916, 361670315347336810428, 3611858972942315054336, 35375586671457852212944
Offset: 0

Views

Author

Vaclav Kotesovec, Mar 10 2010

Keywords

Crossrefs

Extensions

More terms from Jinyuan Wang, Feb 26 2020
a(0)=1 prepended by Andrew Howroyd, Mar 26 2023

A194647 Number of ways to place 5n nonattacking kings on a 10 X 2n cylindrical chessboard.

Original entry on oeis.org

192, 708, 3036, 13932, 66532, 327192, 1649420, 8500668, 44693472, 239238888, 1301236304, 7177627944, 40078823652, 226167613792, 1287874058656, 7390391650172, 42688584938548, 247956702607932, 1447080255512308, 8479116559291112, 49852445684576540
Offset: 1

Views

Author

Vaclav Kotesovec, Aug 31 2011

Keywords

Comments

This cylinder is horizontal: a chessboard where it is supposed that rows 1 and 2n are in contact (number of columns = 10, number of rows = 2n).

Crossrefs

Formula

G.f.: -2*(7089408*x^21 - 132938496*x^20 + 1125112128*x^19 - 5717239392*x^18 + 19578445344*x^17 - 48082847384*x^16 + 88003026752*x^15 - 123138008952*x^14 + 134072006560*x^13 - 114991853490*x^12 + 78336556962*x^11 - 42596878318*x^10 + 18524447581*x^9 - 6435525481*x^8 + 1778018953*x^7 - 387290192*x^6 + 65568715*x^5 - 8436954*x^4 + 796245*x^3 - 51918*x^2 + 2088*x - 39)/((x-1)*(2*x-1)*(4*x-1)*(6*x-1)*(x^2-4*x+1)*(2*x^2-5*x+1)*(2*x^2-4*x+1)*(4*x^2-6*x+1)*(6*x^2-6*x+1)*(7*x^2-6*x+1)*(2*x^3-8*x^2+6*x-1)*(3*x^3-9*x^2+6*x-1)).
Asymptotic: a(n) ~ 2*6^n.

A195593 Number of ways to place 5n nonattacking kings on a vertical cylinder 10 X 2n.

Original entry on oeis.org

64, 732, 4392, 18890, 66532, 205628, 580664, 1536814, 3877300, 9434784, 22327496, 51698178, 117645348, 263992580, 585640568, 1286898262, 2805399156, 6074441896, 13076687560, 28009586346, 59732295204, 126891641612, 268638308152, 566987715710
Offset: 1

Views

Author

Vaclav Kotesovec, Sep 21 2011

Keywords

Comments

Vertical cylinder: a chessboard where it is supposed that the columns 1 and 10 are in contact (number of columns = 10, number of rows = 2n).

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{8, -26, 44, -41, 20, -4}, {64, 732, 4392, 18890, 66532, 205628}, 20] (* Jinyuan Wang, Feb 26 2020 *)

Formula

a(n) = -4*a(n-6) + 20*a(n-5) - 41*a(n-4) + 44*a(n-3) - 26*a(n-2) + 8*a(n-1).
G.f.: (1 + 56*x + 246*x^2 + 156*x^3 + 11*x^4)/((x-1)^4*(2*x-1)^2).
a(n) = (1771*n - 8709)*2^n + 235/3*n^3 + 880*n^2 + 12815/3*n + 8710.
Showing 1-7 of 7 results.