A036464 -id:A036464 - cp's OEIS frontend

A172137 Number of ways to place 2 nonattacking zebras on an n X n board.

0, 6, 36, 112, 276, 582, 1096, 1896, 3072, 4726, 6972, 9936, 13756, 18582, 24576, 31912, 40776, 51366, 63892, 78576, 95652, 115366, 137976, 163752, 192976, 225942, 262956, 304336, 350412, 401526, 458032, 520296, 588696, 663622, 745476, 834672, 931636, 1036806

Offset: 1

Vaclav Kotesovec, Jan 26 2010

Zebra is a (fairy chess) leaper [2,3].

Christian Poisson, Echecs et mathematiques, Rex Multiplex 29/1990, p. 829.

Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Vaclav Kotesovec, Number of ways of placing non-attacking queens and kings on boards of various sizes
Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1).

Cf. A036464, A172123, A172132.

[n eq 1 select 0 else (n^4 -9*n^2 +40*n -48)/2: n in [1..50]]; // G. C. Greubel, Apr 19 2022

CoefficientList[Series[2x(3+3*x-4*x^2+8*x^3-4*x^4)/(1-x)^55, {x, 0, 40}], x] (* Vincenzo Librandi, May 26 2013 *)

[(n^4 -9*n^2 +40*n -48 +16*bool(n==1))/2 for n in (1..50)] # G. C. Greubel, Apr 19 2022

a(n) = (n^4 - 9*n^2 + 40*n - 48)/2, n >= 2. (Christian Poisson, 1990)
G.f.: 2*x^2*(3+3*x-4*x^2+8*x^3-4*x^4)/(1-x)^5. - Vaclav Kotesovec, Mar 25 2010
E.g.f.: (1/2)*(16*(3+x) + (-48 + 32*x - 2*x^2 + 6*x^3 + x^4)*exp(x)). - G. C. Greubel, Apr 19 2022

A172200 Number of ways to place 2 nonattacking amazons (superqueens) on an n X n board.

Original entry on oeis.org

0, 0, 0, 20, 92, 260, 580, 1120, 1960, 3192, 4920, 7260, 10340, 14300, 19292, 25480, 33040, 42160, 53040, 65892, 80940, 98420, 118580, 141680, 167992, 197800, 231400, 269100, 311220, 358092, 410060, 467480, 530720, 600160, 676192, 759220, 849660

Offset: 1

Vaclav Kotesovec, Jan 29 2010

A amazon (superqueen) moves like a queen and a knight.

Christian Poisson, Echecs et mathematiques, Rex Multiplex 29/1990, p.829

Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Vaclav Kotesovec, Number of ways of placing non-attacking queens and kings on boards of various sizes
Index entries for linear recurrences with constant coefficients, signature (5,-10,10,-5,1).

Cf. A036464, A051223, A051224.

[(n-1)*(n-2)*(n-3)*(3*n+8)/6: n in [1..50]]; // Vincenzo Librandi, May 27 2013

CoefficientList[Series[4x^3(5-2x)/(1-x)^5, {x, 0, 40}], x] (* Vincenzo Librandi, May 27 2013 *)
LinearRecurrence[{5,-10,10,-5,1},{0,0,0,20,92},40] (* or *) Table[(n-1)(n-2)(n-3)(3n+8)/6,{n,40}] (* Harvey P. Dale, May 16 2021 *)

[binomial(n-1,3)*(3*n+8) for n in (1..50)] # G. C. Greubel, Apr 28 2022

Explicit formula (Christian Poisson, 1990): a(n) = (n - 1)(n - 2)(n - 3)(3n + 8)/6.
G.f.: 4*x^4*(5-2*x)/(1-x)^5. - Colin Barker, Jan 09 2013
E.g.f.: 8 + (1/6)*(-48 +48*x -24*x^2 +8*x^3 +3*x^4)*exp(x). - G. C. Greubel, Apr 28 2022

A178721 Number of ways to place 7 nonattacking queens on an n X n board.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 40, 3192, 119180, 2119176, 23636352, 186506000, 1131544008, 5613017128, 23670094984, 87463182432, 289367715488, 872345119896, 2427609997716, 6305272324272

Offset: 1

Vaclav Kotesovec, Jun 07 2010

nonn

S. Chaiken, C. R. H. Hanusa and T. Zaslavsky, A q-Queens Problem, I. General theory, Jan 26 2013, updated Feb 21 2014
Christopher R. H. Hanusa, T Zaslavsky, S Chaiken, A q-Queens Problem. IV. Queens, Bishops, Nightriders (and Rooks), arXiv preprint arXiv:1609.00853, a12016
V. Kotesovec, Non-attacking chess pieces, 6ed, 2013
Index entries for linear recurrences with constant coefficients, order 197.

Cf. A036464, A047659, A061994, A108792, A176186, A178717.

Column k=7 of A348129.

(* General formulas (denominator and recurrence) for k nonattacking queens on an n X n board: *) inversef[j_]:=(m=2;While[j>Fibonacci[m],m=m+1];m); denom[k_]:=(x-1)^(2k+1)*Product[Cyclotomic[j,x]^(2*(k-inversef[j]+1)),{j,2,Fibonacci[k]}]; Table[denom[k],{k,1,7}]//TraditionalForm Table[Sum[Coefficient[Expand[denom[k]],x,i]*Subscript[a,n-i],{i,0,Exponent[denom[k],x]}],{k,1,7}]//TraditionalForm

Denominator of G.f.: (x-1)^15*(x+1)^10*(x^2+x+1)^8*(x^2+1)^6*(x^4+x^3+x^2+x+1)^6*(x^2-x+1)^4*(x^6+x^5+x^4+x^3+x^2+x+1)^4*(x^4+1)^4*(x^6+x^3+1)^2*(x^4-x^3+x^2-x+1)^2*(x^10+x^9+x^8+x^7+x^6+x^5+x^4+x^3+x^2+x+1)^2*(x^4-x^2+1)^2*(x^12+x^11+x^10+x^9+x^8+x^7+x^6+x^5+x^4+x^3+x^2+x+1)^2.

Recurrence: a(n) = a(n-197) + 11a(n-196) + 66a(n-195) + 284a(n-194) + 979a(n-193) + 2867a(n-192) + 7391a(n-191) + 17167a(n-190) + 36502a(n-189) + 71854a(n-188) + 132001a(n-187) + 227579a(n-186) + 369573a(n-185) + 566345a(n-184) + 818910a(n-183) + 1114468a(n-182) + 1418684a(n-181) + 1667858a(n-180) + 1762862a(n-179) + 1567406a(n-178) + 913631a(n-177) - 382005a(n-176) - 2490306a(n-175) - 5527702a(n-174) - 9503162a(n-173) - 14258598a(n-172) - 19411273a(n-171) - 24310113a(n-170) - 28020291a(n-169) - 29351159a(n-168) - 26940769a(n-167) - 19405263a(n-166) - 5553140a(n-165) + 15346812a(n-164) + 43268288a(n-163) + 77138720a(n-162) + 114608227a(n-161) + 151932369a(n-160) + 184024666a(n-159) + 204725598a(n-158) + 207315406a(n-157) + 185268748a(n-156) + 133212155a(n-155) + 48004017a(n-154) - 70183102a(n-153) - 216930246a(n-152) - 382960078a(n-151) - 554012366a(n-150) - 711346353a(n-149) - 832955143a(n-148) - 895498622a(n-147) - 876864666a(n-146) - 759163548a(n-145) - 531860790a(n-144) - 194674273a(n-143) + 240182841a(n-142) + 746828188a(n-141) + 1285960424a(n-140) + 1806771216a(n-139) + 2250587298a(n-138) + 2556103772a(n-137) + 2665846492a(n-136) + 2533288725a(n-135) + 2129874995a(n-134) + 1451101463a(n-133) + 520790749a(n-132) - 607206046a(n-131) - 1850443990a(n-130) - 3102719461a(n-129) - 4242198625a(n-128) - 5142328327a(n-127) - 5684628585a(n-126) - 5772140029a(n-125) - 5342085203a(n-124) - 4376237801a(n-123) - 2907601789a(n-122) - 1022286568a(n-121) + 1144093134a(n-120) + 3415602536a(n-119) + 5590244180a(n-118) + 7458159648a(n-117) + 8822115392a(n-116) + 9518231826a(n-115) + 9434741790a(n-114) + 8526633540a(n-113) + 6824351658a(n-112) + 4435274433a(n-111) + 1537407289a(n-110) - 1634445881a(n-109) - 4808938651a(n-108) - 7703022656a(n- 107) - 10048957558a(n-106) - 11620750186a(n-105) - 12257251526a(n-104) - 11879415820a(n-103) - 10499785534a(n-102) - 8223052813a(n-101) - 5237477687a(n-100) - 1797913038a(n-99) + 1797913038a(n-98) + 5237477687a(n-97) + 8223052813a(n-96) + 10499785534a(n-95) + 11879415820a(n-94) + 12257251526a(n-93) + 11620750186a(n-92) + 10048957558a(n-91) + 7703022656a(n-90) + 4808938651a(n-89) + 1634445881a(n-88) - 1537407289a(n-87) - 4435274433a(n-86) - 6824351658a(n-85) - 8526633540a(n-84) - 9434741790a(n-83) - 9518231826a(n-82) - 8822115392a(n-81) - 7458159648a(n-80) - 5590244180a(n-79) - 3415602536a(n-78) - 1144093134a(n-77) + 1022286568a(n-76) + 2907601789a(n-75) + 4376237801a(n-74) + 5342085203a(n-73) + 5772140029a(n-72) + 5684628585a(n-71) + 5142328327a(n-70) + 4242198625a(n-69) + 3102719461a(n-68) + 1850443990a(n-67) + 607206046a(n-66) - 520790749a(n-65) - 1451101463a(n-64) - 2129874995a(n-63) - 2533288725a(n-62) - 2665846492a(n-61) - 2556103772a(n-60) - 2250587298a(n-59) - 1806771216a(n-58) - 1285960424a(n-57) - 746828188a(n-56) - 240182841a(n-55) + 194674273a(n-54) + 531860790a(n-53) + 759163548a(n-52) + 876864666a(n-51) + 895498622a(n-50) + 832955143a(n-49) + 711346353a(n-48) + 554012366a(n-47) + 382960078a(n-46) + 216930246a(n-45) + 70183102a(n-44) - 48004017a(n-43) - 133212155a(n-42) - 185268748a(n-41) - 207315406a(n-40) - 204725598a(n-39) - 184024666a(n-38) - 151932369a(n-37) - 114608227a(n-36) - 77138720a(n-35) - 43268288a(n-34) - 15346812a(n-33) + 5553140a(n-32) + 19405263a(n-31) + 26940769a(n-30) + 29351159a(n-29) + 28020291a(n-28) + 24310113a(n-27) + 19411273a(n-26) + 14258598a(n-25) + 9503162a(n-24) + 5527702a(n-23) + 2490306a(n-22) + 382005a(n-21) - 913631a(n-20) - 1567406a(n-19) - 1762862a(n-18) - 1667858a(n-17) - 1418684a(n-16) - 1114468a(n-15) - 818910a(n-14) - 566345a(n-13) - 369573a(n-12) - 227579a(n-11) - 132001a(n-10) - 71854a(n-9) - 36502a(n-8) - 17167a(n-7) - 7391a(n-6) - 2867a(n-5) - 979a(n-4) - 284a(n-3) - 66a(n-2) - 11a(n-1).

a(19)-a(20) from Vaclav Kotesovec, Jun 16 2010

A174642 Number of ways to place 4 nonattacking amazons (superqueens) on a 4 X n board.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 12, 60, 180, 432, 900, 1692, 2940, 4800, 7452, 11100, 15972, 22320, 30420, 40572, 53100, 68352, 86700, 108540, 134292, 164400, 199332, 239580, 285660, 338112, 397500, 464412, 539460, 623280, 716532, 819900, 934092, 1059840

Offset: 1

Vaclav Kotesovec, Mar 25 2010

An amazon (superqueen) moves like a queen and a knight

Vincenzo Librandi, Table of n, a(n) for n = 1..1000
The Oprisch Family Web Site
V. Kotesovec, Number of ways of placing non-attacking queens and kings on boards of various sizes

Cf. A173214, A172201, A172200, A051223, A051224, A036464.

CoefficientList[Series[- 12 x^7 (x^3 + 1) / (x - 1)^5, {x, 0, 50}], x] (* Vincenzo Librandi, May 30 2013 *)

G.f.: -12*x^8*(x^3+1)/(x-1)^5.

Explicit formula: a(n) = (n-7)(n^3-21n^2+158n-420), n>=7.

More terms from Vincenzo Librandi, May 30 2013

A178717 Degree of denominator of GF for number of ways to place k nonattacking queens on an n X n board.

Original entry on oeis.org

3, 5, 9, 17, 37, 81, 197, 477, 1197, 3077, 7989, 20649, 53885, 140601, 366917, 959685, 2511477, 6571681, 17202449, 45027677, 117871345, 308581637, 807852685, 2114904397, 5536838045, 14495554593, 37949503089, 99352690141, 260108204933

Offset: 1

Vaclav Kotesovec, Jun 07 2010

nonn

V. Kotesovec, Non-attacking chess pieces, 6ed, 2013

Cf. A036464, A047659, A061994, A108792, A176186, A000010, A000045.

Table[2*k + 1 + Sum[Sum[2*j*EulerPhi[i], {i, Fibonacci[k - j] + 1, Fibonacci[k - j + 1]}], {j, 1, k - 1}], {k, 1, 20}]

Explicit formula (Vaclav Kotesovec, May 31 2010), for k>1 : d(k) = 2*k+1+Sum[Sum[2*j*EulerPhi[i],{i,Fibonacci[k-j]+1,Fibonacci[k-j+1]}],{j,1,k-1}].

Asymptotic formula: d(k) ~ 6/(5*Pi^2)*((1+Sqrt[5])/2)^(2*k+1) or d(k) ~ 3*(1+Sqrt[5])/Pi^2*Fibonacci[k]^2.

A252593 Number of ways to place 8 nonattacking queens on an n X n board.

Original entry on oeis.org

0, 0, 0, 0, 0, 0, 0, 92, 13848, 636524, 14803480, 207667564, 2008758532, 14752426528, 87154016752, 432539436508, 1858901487620

Offset: 1

Antal Pinter, Dec 18 2014

Conjectured recurrence order is 477 (see "Non-attacking chess pieces", p. 19). - Vaclav Kotesovec, Dec 19 2014

S. Chaiken, C. R. H. Hanusa and T. Zaslavsky, A q-Queens Problem, I. General theory, arXiv:1303.1879 [math.CO], 2013-2014.
V. Kotesovec, Non-attacking chess pieces, 6ed, 2013
Antal Pinter, Combinatorics, software for enumerating positions of non-attacking chess pieces.
I. Rivin, I. Vardi and P. Zimmermann, The n-queens problem, Amer. Math. Monthly, 101 (1994), 629-639.

Cf. A000170, A036464, A047659, A061994, A108792, A176186, A178721.

Column k=8 of A348129.

a(n) = n^16/40320 - n^15/432 + 221*n^14/2160 + O(n^13). - Vaclav Kotesovec, Dec 19 2014

a(16) from Vaclav Kotesovec, Dec 19 2014

a(17) from Vaclav Kotesovec, Dec 20 2014

A269133 Number of ways to place m nonattacking queens on an m X n board, 1 <= m <= n (triangular array).

Original entry on oeis.org

1, 2, 0, 3, 2, 0, 4, 6, 4, 2, 5, 12, 14, 12, 10, 6, 20, 36, 46, 40, 4, 7, 30, 76, 140, 164, 94, 40, 8, 42, 140, 344, 568, 550, 312, 92, 9, 56, 234, 732, 1614, 2292, 2038, 1066, 352, 10, 72, 364, 1400, 3916, 7552, 9632, 7828, 4040, 724, 11, 90, 536, 2468, 8492, 21362, 37248, 44148, 34774, 15116, 2680, 12, 110, 756, 4080, 16852, 52856, 120104, 195270, 222720, 160964, 68264, 14200

Offset: 1

Marko Riedel, Feb 19 2016

			The triangular array begins:
   n\m  1   2   3    4     5     6      7      8      9     10    11    12
   1    1
   2    2   0
   3    3   2   0
   4    4   6   4    2
   5    5  12  14   12    10
   6    6  20  36   46    40     4
   7    7  30  76  140   164    94     40
   8    8  42 140  344   568   550    312     92
   9    9  56 234  732  1614  2292   2038   1066    352
  10   10  72 364 1400  3916  7552   9632   7828   4040    724
  11   11  90 536 2468  8492 21362  37248  44148  34774  15116  2680
  12   12 110 756 4080 16852 52856 120104 195270 222720 160964 68264 14200
...

Math StackExchange, State space for eight queen problem
Marko Riedel, Perl program to compute triangular array of nonattacking queens configurations

Cf. A000170 (m=n), A002562, A065256, A348129.
Cf. A000027 (m=1), A002378 (m=2), A061989 (m=3), A061990 (m=4), A061991 (m=5), A061992 (m=6), A061993 (m=7), A172449 (m=8).
Cf. A036464 (2Q), A047659 (3Q), A061994 (4Q), A108792 (5Q), A176186 (6Q).
Cf. A006717, A051906, A319284 (backtrack trees).

{A269133(m, n, B=[], t=if(#B, setminus(n, Set(concat(B+t=[-#B..-1], B-t))), n=[1..n]))= if(#B < m-1, vecsum([A269133(m, setminus(n, [t]), concat(B,t)) | t<-t]), #t)} \\ M. F. Hasler, Jan 11 2022

A344227 Sprague-Grundy value for the Node-Kayles game played on the n-queens graph.

Original entry on oeis.org

0, 1, 1, 2, 1, 3, 1, 2, 3, 1, 0, 1, 0, 1

Offset: 0

Max Fan and Matthew K. Bardoe, May 13 2021

This game is also known as the Non-Attacking Queens game. Rules: two players successively place queens on an n X n chessboard such that the queens do not attack each other. The last player to place a queen wins.
Empirically, it appears that after the 9th term, the sequence oscillates between 1 and 0.
The n-queens graph considered here is not vertex-transitive. However, the toroidal version is and for Node-Kayles played on graphs that are vertex-transitive, it can be proven that the Sprague-Grundy value must be either 0 or 1.
Proof:
Each node in a graph that is transitive for all vertices has the same Sprague-Grundy value, since removing any node and its neighbors will produce identical graphs up to isomorphism.
This Sprague-Grundy value of the new graph must be either zero or nonzero.
If zero, then by the minimum exclusion principle, the value of the original graph is 1.
If nonzero, then by the minimum exclusion principle, the value of the original graph is 0.
Therefore, the Sprague-Grundy value of the original, vertex-transitive graph must be either 0 or 1.

G. Schrage, The eight queens problem as a strategy game, Int. J. Math. Educ. Sci. Technol. 17 (1989) 143-148. (mentions a restricted form of the Non-Attacking Queens game).

Matthew Bardoe, Non-Attacking Queens implementation in Python on Torus and non-Torus Chessboards.
Max Fan, Generalized Node-Kayles calculator implemented in Rust (terms 0 and terms 11-13 from Max Fan).
H. Noon, Surreal Numbers and the N-Queens Game, Bennington College, 2002 (includes this sequence).
H. Noon and G. Brummelen, The Non-Attacking Queens Game, The College Mathematics Journal., 224 (2006), 223-227 (Original problem description, terms 1-10 from H. Noon).

Cf. A000170, A002562, A036464, A316533, A316632, A316781, A002186.

pickCoords n = sequence (replicate 2 [0..n-1])
mex list = head (filter (`notElem` list) [0..(maximum list+1)])
checkIntersect [x,y] [n,m] = not (x == n || y == m) && (abs (x-n) /= abs (y-m))
nextMoves max history = filter (\move -> null history || all (checkIntersect move) history) (pickCoords max)
calcNimber max history | null (nextMoves max history) = 0 | otherwise = mex (map (\move -> calcNimber max (history ++ [move])) (nextMoves max history))
a344227 n = calcNimber n []

Rust
```
// See Fan link.
```

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A172137 Number of ways to place 2 nonattacking zebras on an n X n board.

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A172200 Number of ways to place 2 nonattacking amazons (superqueens) on an n X n board.

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A178721 Number of ways to place 7 nonattacking queens on an n X n board.

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A174642 Number of ways to place 4 nonattacking amazons (superqueens) on a 4 X n board.

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A178717 Degree of denominator of GF for number of ways to place k nonattacking queens on an n X n board.

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A252593 Number of ways to place 8 nonattacking queens on an n X n board.

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A269133 Number of ways to place m nonattacking queens on an m X n board, 1 <= m <= n (triangular array).

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A344227 Sprague-Grundy value for the Node-Kayles game played on the n-queens graph.

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