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 14 results. Next

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

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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

A061593 Number of ways to place 2n nonattacking kings on a 4 X 2n chessboard.

Original entry on oeis.org

12, 79, 408, 1847, 7698, 30319, 114606, 419933, 1501674, 5266069, 18174084, 61892669, 208424880, 695179339, 2299608732, 7552444115, 24648046806, 79994460139, 258339007890, 830619734681, 2660070154542, 8488515938929, 27000079296648, 85629004867577
Offset: 1

Views

Author

Antonio G. Astudillo (afg_astudillo(AT)hotmail.com), May 22 2001

Keywords

Crossrefs

Column k=2 of A350819.

Programs

  • Magma
    [(17*n-109)*3^n+2*Fibonacci(2*n+10): n in [1..30]]; // Vincenzo Librandi, Jul 12 2011
  • Maple
    with(combinat): A061593:=n->(17*n-109)*3^n+2*fibonacci(2*n+10): seq(A061593(n), n=1..30); # Wesley Ivan Hurt, Nov 08 2014
  • Mathematica
    Table[(17 n - 109)*3^n + 2 Fibonacci[2 n + 10], {n, 30}] (* Wesley Ivan Hurt, Nov 08 2014 *)
    CoefficientList[Series[x (12-29x+33x^2-9x^3)/((1-3x+x^2)(1-3x)^2),{x,0,30}],x] (* or *) LinearRecurrence[{9,-28,33,-9},{0,12,79,408,1847},30] (* Harvey P. Dale, Dec 20 2021 *)

Formula

G.f.: x*(12-29*x+33*x^2-9*x^3)/((1-3*x+x^2)*(1-3*x)^2).
a(n) = 9*a(n-1) - 28*a(n-2) + 33*a(n-3) - 9*a(n-4); a(1)=12, a(2)=79, a(3)=408, a(4)=1847.
a(n) = (17*n-109)*3^n + 2*Fibonacci(2*n+10).
a(n) = 17*A027471(n+2) - 126*A000244(n) + A025169(n+4).

A061594 Number of ways to place 3n nonattacking kings on a 6 X 2n chessboard.

Original entry on oeis.org

1, 32, 408, 3600, 26040, 166368, 976640, 5392704, 28432288, 144605184, 714611200, 3449705600, 16333065216, 76081271168, 349524164224, 1586790140800, 7130144209024, 31752978219904, 140298397039232, 615604372260736
Offset: 0

Views

Author

Antonio G. Astudillo (afg_astudillo(AT)hotmail.com), May 22 2001

Keywords

Crossrefs

Column k=3 of A350819.
Equals 231*A002697(n+1) - 2608*A000302(n) - 384*A000244(n) + 1103*A007070(n-1) + 780*A006012(n+1) + (n+1)*(17*A048580(n) + 12*A007070(n+1)).

Programs

  • PARI
    a(n)=polcoeff((1+13*x-52*x^2-20*x^3+60*x^4-20*x^5)/((1-3*x)*(1-4*x)^2*(1-4*x+2*x^2)^2)+x*O(x^n),n)

Formula

G.f.: (1+13x-52x^2-20x^3+60x^4-20x^5)/((1-3x)(1-4x)^2(1-4x+2x^2)^2).
Explicit formula: (231n-2377)*4^n - 384*3^n + (1953*sqrt(2)/2+1381+(35*sqrt(2)+99/2)*n)*(2+sqrt(2))^n + (1381-1953*sqrt(2)/2+(99/2-35*sqrt(2))*n)*(2-sqrt(2))^n. - Vaclav Kotesovec, Feb 06 2010

Extensions

Corrected data by Vincenzo Librandi, Oct 12 2011

A173782 Number of ways to place 4n nonattacking kings on an 8 X 2n chessboard.

Original entry on oeis.org

80, 1847, 26040, 281571, 2580754, 21137959, 159636030, 1134127305, 7683664202, 50123713793, 317076250136, 1955475353217, 11806000507544, 70004699407151, 408747986045656, 2355077855615435, 13413115039118042, 75623103424916527
Offset: 1

Views

Author

Vaclav Kotesovec, Feb 24 2010

Keywords

Crossrefs

Column k=4 of A350819.

Programs

  • Mathematica
    CoefficientList[Series[(22500 x^16 - 382125 x^15 + 2723005 x^14 - 10917322 x^13 + 27938661 x^12 - 48873227 x^11 + 60780149 x^10 - 54895129 x^9 + 36368733 x^8 - 17776175 x^7 + 6499001 x^6 - 1854479 x^5 + 446565 x^4 - 94300 x^3 + 15732 x^2 - 1673 x + 80) / ((1 - x) (x^2 - 4 x + 1) (x^3 - 6 x^2 + 5 x - 1) (4 x - 1) (5 x - 1)^2 (3 x^2 - 5 x + 1)^2 (5 x^2 - 5 x + 1)^2),{x, 0, 50}], x] (* Vincenzo Librandi, May 30 2013 *)

Formula

G.f.: x*(22500*x^16 -382125*x^15 +2723005*x^14 -10917322*x^13 +27938661*x^12 -48873227*x^11 +60780149*x^10 -54895129*x^9 +36368733*x^8 -17776175*x^7 +6499001*x^6 -1854479*x^5+446565*x^4 -94300*x^3 +15732*x^2 -1673*x+80) / ((1-x) *(x^2-4*x+1) *(x^3-6*x^2+5*x-1) *(4*x-1) *(5*x-1)^2 *(3*x^2-5*x+1)^2 *(5*x^2-5*x+1)^2).
Recurrence: a(n) = 44a(n-1) -887a(n-2) +10855a(n-3) -90083a(n-4) +536398a(n-5) -2365292a(n-6) +7860674a(n-7) -19852652a(n-8) +38152568a(n-9) -55523880a(n-10) +60518766a(n-11) -48502595a(n-12) +27783210a(n-13) -10888525a(n-14) +2721025a(n-15) -382125a(n-16) +22500a(n-17), n>17.
a(n) = (-12505804889/302760 +7963567/2610*n)*5^n +3872/3*4^n -1/24 +(135343*sqrt(3)/18 -234421/18)*(2 -sqrt(3))^n -(135343*sqrt(3)/18 +234421/18)*(2 +sqrt(3))^n +(33301/5 -74461*sqrt(5)/25 +(141*sqrt(5)/25 -63/5)*n)*((5 -sqrt(5))/2)^n +(74461*sqrt(5)/25 +33301/5 - (141*sqrt(5)/25 + 63/5)*n)*((5 +sqrt(5))/2)^n + (4306740/169 - 1194474*sqrt(13)/169 + (139103/117 - 501541*sqrt(13)/1521)*n)*((5 -sqrt(13))/2)^n +(1194474*sqrt(13)/169 +4306740/169 +(501541*sqrt(13)/1521 +139103/117)*n)*((5 +sqrt(13))/2)^n +72*(b*(3504697*c - 11380560) -11380560*c +36953816)/(142129*(a - b)*(a - c))*a^n +72*(a*(3504697*c - 11380560) - 8*(1422570*c - 4619227))/(142129*(a - b)*(c - b))*b^n +72*(a*(3504697*b - 11380560) -8*(1422570*b - 4619227))/(142129*(a - c)*(b - c))*c^n, where: a=2-2*sin(Pi/14), b=2+2*sin(3*Pi/14), c=2-2*cos(Pi/7). - Vaclav Kotesovec, added Mar 01 2010, updated Mar 29 2010.

A173783 Number of ways to place 5n nonattacking kings on a 10 X 2n chessboard.

Original entry on oeis.org

192, 7698, 166368, 2580754, 32572756, 357365350, 3544192112, 32580145116, 282359109140, 2335042206624, 18589546217696, 143422674213726, 1077891352444220, 7923134615854816, 57146364209686016, 405497952834408698
Offset: 1

Views

Author

Vaclav Kotesovec, Feb 24 2010

Keywords

Crossrefs

Column k=5 of A350819.

Programs

  • Mathematica
    CoefficientList[Series[2 (292626432 x^30 - 7695378432 x^29 + 94084706304 x^28 - 712519981056 x^27 + 3757888797696 x^26 - 14715718076160 x^25 + 44556058968960 x^24 - 107273952716256 x^23 + 209645023363168 x^22 - 337824014576768 x^21 + 454329405135504 x^20 - 514643686425920 x^19 + 494203416082160 x^18 - 403847150294172 x^17 + 281135354205764 x^16 - 166453721883480 x^15 + 83456844800670 x^14 - 35182845104124 x^13 + 12345883162136 x^12 - 3557728594620 x^11 + 827346101101 x^10 - 152042822189 x^9 + 21726065190 x^8 - 2499103126 x^7 + 289877178 x^6 - 45817212 x^5 + 7810422 x^4 - 1012942 x^3 + 86355 x^2 - 4311 x + 96) / ((1 - 2 x) (x^2 - 4 x + 1) (4 x - 1) (6 x - 1)^2 (2 x^2 - 4 x + 1) (2 x^2 - 5 x + 1) (4 x^2 - 6 x + 1)^2 (6 x^2 - 6 x + 1)^2 (7 x^2 - 6 x + 1)^2 (2 x^3 - 8 x^2 + 6 x - 1) (3 x^3 - 9 x^2 + 6 x - 1)^2), {x, 0, 50}], x] (* Vincenzo Librandi, May 30 2013 *)

Formula

G.f.: 2*x*(292626432*x^30 -7695378432*x^29 +94084706304*x^28 -712519981056*x^27 +3757888797696*x^26 -14715718076160*x^25 +44556058968960*x^24 -107273952716256*x^23 +209645023363168*x^22 -337824014576768*x^21 +454329405135504*x^20 -514643686425920*x^19 +494203416082160*x^18 -403847150294172*x^17 +281135354205764*x^16 -166453721883480*x^15 +83456844800670*x^14 -35182845104124*x^13 +12345883162136*x^12 -3557728594620*x^11 +827346101101*x^10 -152042822189*x^9 +21726065190*x^8 -2499103126*x^7 +289877178*x^6 -45817212*x^5 +7810422*x^4 -1012942*x^3 +86355*x^2 -4311*x+96) / ((1-2*x) *(x^2-4*x+1) *(4*x-1) *(6*x-1)^2 *(2*x^2-4*x+1) *(2*x^2-5*x+1) *(4*x^2-6*x+1)^2 *(6*x^2-6*x+1)^2 *(7*x^2-6*x+1)^2 *(2*x^3-8*x^2+6*x-1) *(3*x^3-9*x^2+6*x-1)^2).
Recurrence: a(n) = 85a(n-1) -3441a(n-2) +88303a(n-3) -1613002a(n-4) +22327010a(n-5) -243429637a(n-6) +2145452227a(n-7) -15565947848a(n-8) +94202823084a(n-9) -480152808502a(n-10) +2075863416838a(n-11) -7651361422835a(n-12) +24128330540449a(n-13) -65240466585284a(n-14) +151411770874148a(n-15) -301613628545814a(n-16) +515173613407544a(n-17) -753006145475828a(n-18) +939001403456656a(n-19) -994821988961592a(n-20) +890558910282768a(n-21) -668920434927504a(n-22) +417832289937792a(n-23) -214574645977920a(n-24) +89258591798784a(n-25) -29486236792320a(n-26) +7526493775872a(n-27) -1426182018048a(n-28) +188221833216a(n-29) -15390756864a(n-30) +585252864a(n-31), n>31.

A350815 Array read by antidiagonals: T(m,n) is the number of minimum dominating sets in the m X n king graph.

Original entry on oeis.org

1, 2, 2, 1, 4, 1, 4, 2, 2, 4, 3, 16, 1, 16, 3, 1, 12, 4, 4, 12, 1, 8, 4, 3, 256, 3, 4, 8, 4, 64, 1, 144, 144, 1, 64, 4, 1, 32, 8, 16, 79, 16, 8, 32, 1, 13, 8, 4, 4096, 9, 9, 4096, 4, 8, 13, 5, 208, 1, 1024, 1656, 1, 1656, 1024, 1, 208, 5, 1, 80, 13, 64, 408, 64, 64, 408, 64, 13, 80, 1
Offset: 1

Views

Author

Andrew Howroyd, Jan 17 2022

Keywords

Comments

The minimum size of a dominating set is the domination number which in the case of an m X n king graph is given by (ceiling(m/3) * ceiling(n/3)).

Examples

			Table begins:
============================================
m\n | 1  2  3    4    5   6      7     8
----+---------------------------------------
  1 | 1  2  1    4    3   1      8     4 ...
  2 | 2  4  2   16   12   4     64    32 ...
  3 | 1  2  1    4    3   1      8     4 ...
  4 | 4 16  4  256  144  16   4096  1024 ...
  5 | 3 12  3  144   79   9   1656   408 ...
  6 | 1  4  1   16    9   1     64    16 ...
  7 | 8 64  8 4096 1656  64 243856 29744 ...
  8 | 4 32  4 1024  408  16  29744  3600 ...
     ...
		

Crossrefs

Rows 1..3 are A347633, A350816, A347633.
Main diagonal is A347554.
Cf. A075561, A218663 (dominating sets), A286849 (minimal dominating sets), A303335, A350818, A350819.

Formula

T(n,m) = T(m,n).
T(3*m, 3*n) = 1; T(3*m+1, 3*n) = (m^2 + 5*m + 2)^n; T(3*m+2, 3*n) = (m+2)^n.
T(3*m-1, 3*n-1) = A350819(m, n).

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

A195648 Number of ways to place 9n nonattacking kings on a 18 x 2n chessboard.

Original entry on oeis.org

5120, 1501674, 144605184, 7683664202, 282359109140, 8080813574550, 193194265398240, 4035559337688370, 75925129079783308, 1314578079936797520, 21279238303065874504, 325878859655043000344, 4765036384361599508980, 67005992305769489072298, 911373843678367079288192
Offset: 1

Views

Author

Vaclav Kotesovec, Sep 22 2011

Keywords

Crossrefs

Column k=9 of A350819.

Formula

Recurrence order is 548.
Showing 1-10 of 14 results. Next