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 1-5 of 5 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).

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

A195004 Number of ways to place 7n nonattacking kings on a 14 X 2n cylindrical chessboard.

Original entry on oeis.org

1024, 4100, 19648, 103508, 580664, 3419648, 20984924, 133538996, 877751236, 5937279840, 41180193352, 291859775552, 2106967145904, 15448890481568, 114765555945488, 861942483797204, 6533144250310688, 49899718750389380, 383593821097441412, 2964842429047018248
Offset: 1

Views

Author

Vaclav Kotesovec, Sep 07 2011

Keywords

Comments

This cylinder is horizontal: a chessboard where it is supposed that rows 1 and 2n are in contact (number of columns = 14, number of rows = 2n).

Crossrefs

A195595 Number of ways to place 7n nonattacking kings on a vertical cylinder 14 X 2n.

Original entry on oeis.org

256, 6060, 58776, 358564, 1649420, 6286658, 20984924, 63558566, 178909300, 476033636, 1212120160, 2980927200, 7129922604, 16675350430, 38293956836, 86629645122, 193553210580, 427974677968, 938053730248, 2040792091884, 4411561365324, 9483844861978
Offset: 1

Views

Author

Vaclav Kotesovec, Sep 21 2011

Keywords

Comments

Vertical cylinder: a chessboard where it is supposed that the columns 1 and 14 are in contact (number of columns = 14, number of rows = 2n).

Crossrefs

Formula

Recurrence: a(n) = -4*a(n-8) + 28*a(n-7) - 85*a(n-6) + 146*a(n-5) - 155*a(n-4) + 104*a(n-3) - 43*a(n-2) + 10*a(n-1).
G.f.: (1 + 246*x + 3543*x^2 + 9080*x^3 + 4915*x^4 + 442*x^5 + 15*x^6)/((x-1)^6*(2*x-1)^2).
a(n) = (157823*n - 1211433)*2^n + 9121/60*n^5 + 35581/12*n^4 + 352625/12*n^3 + 2179835/12*n^2 + 20456597/30*n + 1211434.
Showing 1-5 of 5 results.