A278688
Triangle read by rows T(n, k) = number of non-equivalent ways to place k non-attacking ferses on an n X n board.
Original entry on oeis.org
1, 1, 1, 1, 1, 1, 3, 6, 7, 6, 2, 1, 1, 3, 17, 45, 92, 99, 76, 27, 7, 1, 6, 43, 225, 832, 2102, 3773, 4860, 4643, 3356, 1868, 795, 248, 56, 8, 1, 1, 6, 84, 709, 4500, 19987, 66201, 164423, 314224, 465230, 540247, 492206, 352300, 195717, 83247, 26083, 5754, 780, 55
Offset: 1
Triangle begins:
1, 1;
1, 1, 1;
1, 3, 6, 7, 6, 2, 1;
1, 3, 17, 45, 92, 99, 76, 27, 7;
Cf.
A008805,
A232567,
A278682,
A278683,
A278684,
A278685,
A278686, (columns 2 through 8 of this sequence, respectively),
A278687,
A093005 (row length - 1).
A278682
Number of non-equivalent ways to place 3 non-attacking ferses on an n X n board.
Original entry on oeis.org
0, 0, 7, 45, 225, 709, 1974, 4524, 9614, 18382, 33425, 56895, 93447, 146715, 224280, 331814, 480844, 679724, 945099, 1288737, 1733725, 2296065, 3006762, 3886960, 4977210, 6304794, 7921589, 9862099, 12191459, 14952567, 18225900, 22064010, 26564952, 31792280
Offset: 1
There are 7 ways to place 3 non-attacking ferses "X" on a 3 X 3 board, rotations and reflections being ignored
XXX XX. X.X ... X.. X.. X..
... ... ... XXX X.X ... ...
... ..X .X. ... ... XX. X.X
- Heinrich Ludwig, Table of n, a(n) for n = 1..1000
- Wikipedia, Fairy chess piece
- Index entries for linear recurrences with constant coefficients, signature (3,1,-11,6,14,-14,-6,11,-1,-3,1).
-
Table[Boole[n > 2] ((n^6 - 15 n^4 + 32 n^3 + 14 n^2 - 116 n + 96) + Boole[OddQ@ n] (8 n^3 - 9 n^2 - 20 n + 9))/48, {n, 34}] (* Michael De Vlieger, Nov 30 2016 *)
-
concat(vector(2), Vec(x^3*(7 + 24*x + 83*x^2 + 66*x^3 + 75*x^4 - 15*x^6 - 2*x^7 + 2*x^8) / ((1 - x)^7*(1 + x)^4) + O(x^40))) \\ Colin Barker, Dec 07 2016
A278683
Number of non-equivalent ways to place 4 non-attacking ferses on an n X n board.
Original entry on oeis.org
0, 0, 6, 92, 832, 4500, 18229, 58881, 163509, 401259, 898420, 1861146, 3625546, 6694982, 11829267, 20099815, 33036079, 52700901, 81916834, 124362664, 184907220, 269726216, 386776561, 545930397, 759628777, 1043027055, 1414873104, 1897655046, 2518755934, 3310591194
Offset: 1
There are 6 ways to place 4 non-attacking ferses on a 3 X 3 board rotations and reflections being ignored:
XXX XXX X.X X.X XX. XX.
... ... ... ... ... ...
..X .X. X.X XX. XX. .XX
- Heinrich Ludwig, Table of n, a(n) for n = 1..1000
- Index entries for linear recurrences with constant coefficients, signature (4,-1,-16,19,20,-45,0,45,-20,-19,16,1,-4,1).
-
Table[Boole[n > 2] (n^8 - 30 n^6 + 48 n^5 + 328 n^4 - 1056 n^3 - 200 n^2 + 4176 n - 4032 + Boole[OddQ@ n] (14 n^4 - 48 n^3 - 38 n^2 + 336 n - 459))/192, {n, 30}] (* Michael De Vlieger, Nov 30 2016 *)
-
concat(vector(2), Vec(x^3*(6 +68*x +470*x^2 +1360*x^3 +2419*x^4 +1909*x^5 +836*x^6 -232*x^7 -192*x^8 +30*x^9 +54*x^10 -9*x^12 +x^13) / ((1 -x)^9*(1 +x)^5) + O(x^40))) \\ Colin Barker, Dec 10 2016
A278684
Number of non-equivalent ways to place 5 non-attacking ferses on an n X n board.
Original entry on oeis.org
0, 0, 2, 99, 2102, 19987, 124676, 571418, 2122841, 6704061, 18711691, 47235845, 109938296, 238950999, 490309398, 957267228, 1790325363, 3224010105, 5615368229, 9493358359, 15627413290, 25112609019, 39484650296, 60859027054, 92114682749, 137111560949, 200972392655
Offset: 1
There are 2 ways to place 5 non-attacking ferses on a 3 X 3 board, rotations and reflections being ignored:
XXX XXX
... ...
X.X XX.
- Heinrich Ludwig, Table of n, a(n) for n = 1..1000
- Wikipedia, Fairy chess piece
- Index entries for linear recurrences with constant coefficients, signature (5,-4,-20,40,16,-100,44,110,-110,-44,100,-16,-40,20,4,-5,1).
-
[0, 0, 2] cat [(n^10 - 50*n^8 + 80*n^7 + 955*n^6 - 2828*n^5 - 7090*n^4 + 36860*n^3 - 10856*n^2 - 133712*n + 161280 + ((1-(-1)^n)/2)*(52*n^5 - 145*n^4 - 580*n^3 + 2320*n^2 - 1152*n - 15))/960 : n in [4..30]]; // Wesley Ivan Hurt, Nov 27 2016
-
A278684:=n->(n^10 - 50*n^8 + 80*n^7 + 955*n^6 - 2828*n^5 - 7090*n^4 + 36860*n^3 - 10856*n^2 - 133712*n + 161280 + ((1-(-1)^n)/2)*(52*n^5 - 145*n^4 - 580*n^3 + 2320*n^2 - 1152*n - 15))/960: 0, 0, 2, seq(A278684(n), n=4..30); # Wesley Ivan Hurt, Nov 27 2016
-
Join[{0, 0, 2}, Table[(n^10 - 50*n^8 + 80*n^7 + 955*n^6 - 2828*n^5 - 7090*n^4 + 36860*n^3 - 10856*n^2 - 133712*n + 161280 + ((1-(-1)^n)/2)*(52*n^5 - 145*n^4 - 580*n^3 + 2320*n^2 - 1152*n - 15))/960, {n, 4, 30}]] (* Wesley Ivan Hurt, Nov 27 2016 *)
-
concat(vector(2), Vec(x^3*(2 +89*x +1615*x^2 +9913*x^3 +35049*x^4 +66034*x^5 +78731*x^6 +45748*x^7 +9902*x^8 -5540*x^9 -1343*x^10 +1685*x^11 +409*x^12 -334*x^13 -83*x^14 +38*x^15 +6*x^16 -x^17) / ((1 -x)^11*(1 +x)^6) + O(x^40))) \\ Colin Barker, Dec 10 2016
A278685
Number of non-equivalent ways to place 6 non-attacking ferses on an n X n board.
Original entry on oeis.org
0, 0, 1, 76, 3773, 66201, 651193, 4318451, 21754341, 89267490, 312974387, 968069337, 2704548145, 6942663519, 16594368633, 37311795887, 79570707969, 162013125016, 316669793867, 596873304925, 1089009784181, 1929545889877, 3329316638249, 5607471933963, 9238336533613
Offset: 1
There is 1 way to place 6 non-attacking ferses on a 3 X 3 board, rotations and reflections being ignored:
XXX
...
XXX
- Heinrich Ludwig, Table of n, a(n) for n = 1..1000
- Wikipedia, Fairy chess piece
- Index entries for linear recurrences with constant coefficients, signature (6,-8,-22,69,-8,-176,168,182,-364,0,364,-182,-168,176,8,-69,22,8,-6,1).
-
concat(vector(2), Vec(x^3*(1 +70*x +3325*x^2 +44193*x^3 +285774*x^4 +1018671*x^5 +2250048*x^6 +3090821*x^7 +2658486*x^8 +1198906*x^9 +139256*x^10 -84845*x^11 +22114*x^12 +28024*x^13 -6172*x^14 -5377*x^15 +485*x^16 +592*x^17 +199*x^18 -56*x^19 -44*x^20 +9*x^21) / ((1 -x)^13*(1 +x)^7) + O(x^30))) \\ Colin Barker, Dec 10 2016
A232569
Triangle T(n, k) = number of non-equivalent (mod D_4) binary n X n matrices with k pairwise not adjacent 1's; k=0,...,n^2.
Original entry on oeis.org
1, 1, 1, 1, 1, 0, 0, 1, 3, 6, 6, 3, 1, 0, 0, 0, 0, 1, 3, 17, 40, 62, 45, 20, 4, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 6, 43, 210, 683, 1425, 1936, 1696, 977, 366, 101, 21, 5, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 6, 84, 681, 4015, 16149, 46472, 95838, 143657
Offset: 1
Triangle begins:
1,1;
1,1,1,0,0;
1,3,6,6,3,1,0,0,0,0;
1,3,17,40,62,45,20,4,1,0,0,0,0,0,0,0,0;
1,6,43,210,683,1425,1936,1696,977,366,101,21,5,1,0,0,0,0,0,0,0,0,0,0,0,0;
...
There are T(3, 2) = 6 non-equivalent binary 3 X 3 matrices with 2 not adjacent 1's (and no other 1's):
[1 0 0] [0 1 0] [1 0 0] [0 1 0] [1 0 1] [1 0 0]
|0 0 0| |0 0 0| |0 1 0| |1 0 0| |0 0 0| |0 0 1|
[0 0 1] [0 1 0] [0 0 0] [0 0 0] [0 0 0] [0 0 0]
A278686
Number of non-equivalent ways to place 7 non-attacking ferses on an n X n board.
Original entry on oeis.org
0, 0, 0, 27, 4860, 164423, 2651890, 25981150, 180378380, 971905679, 4316504623, 16457726539, 55463445891, 168782705327, 471407278652, 1223710587908, 2982045310010
Offset: 1
There are 27 non-equivalent ways to place 7 non-attacking ferses (X) on a 4 X 4 board, rotations and reflections being ignored, e.g., these two:
XXXX X.XX
.... ....
XXX. X.X.
.... X.X.
A232568
Number of non-equivalent binary n X n matrices with three pairwise nonadjacent 1's.
Original entry on oeis.org
0, 6, 40, 210, 681, 1919, 4443, 9481, 18206, 33164, 56570, 92996, 146175, 223565, 330981, 479779, 678508, 943586, 1287036, 1731654, 2293765, 3004011, 3883935, 4973645, 6300906, 7917064, 9857198, 12185816, 14946491, 18218969, 22056585, 26556551, 31783320
Offset: 2
There are a(3) = 6 non-equivalent 3 X 3 matrices with three pairwise nonadjacent 1's (and no other 1's):
[1 0 0] [1 0 1] [1 0 0] [1 0 1] [1 0 1] [0 1 0]
|0 1 0| |0 0 0| |0 0 1| |0 0 0| |0 1 0| |1 0 1|
[0 0 1] [1 0 0] [0 1 0] [0 1 0] [0 0 0] [0 0 0]
- Heinrich Ludwig, Table of n, a(n) for n = 2..1001
- Index entries for linear recurrences with constant coefficients, signature (3,1,-11,6,14,-14,-6,11,-1,-3,1).
-
A232568:=n->(n^6-15*n^4+28*n^3+29*n^2-76*n-15-((n+1) mod 2)*(8*n^3-21*n^2+40*n-63))/48; seq(A232568(n), n=2..50); # Wesley Ivan Hurt, Dec 06 2013
-
Table[(n^6-15n^4+28n^3+29n^2-76n-15-Mod[n+1,2](8n^3-21n^2+40n-63))/48, {n, 2, 50}] (* Wesley Ivan Hurt, Dec 06 2013 *)
A239576
Number of non-equivalent (mod D_4) binary n X n matrices with 4 pairwise nonadjacent 1's.
Original entry on oeis.org
0, 3, 62, 683, 4015, 16989, 56196, 158271, 391917, 882683, 1836106, 3587103, 6638267, 11747613, 19985680, 32879339, 52490521, 81638211, 124000342, 184440963, 269135111, 386033453, 545007772, 758491143, 1041639045, 1413189339, 1895630946, 2516334551, 3307717267
Offset: 2
There are a(3) = 3 non-equivalent binary 3 X 3 matrices with 4 pairwise nonadjacent 1s (x):
[0 1 0] [1 0 1] [1 0 1]
|1 0 1| |0 1 0| |0 0 0|
[0 1 0] [1 0 0] [1 0 1]
- Heinrich Ludwig, Table of n, a(n) for n = 2..1000
- Index entries for linear recurrences with constant coefficients, signature (4,-1,-16,19,20,-45,0,45,-20,-19,16,1,-4,1)
-
Flatten[{0,Table[(n^8-30*n^6+24*n^5+352*n^4-576*n^3-1280*n^2+3360*n-1536+If[EvenQ[n],0,(14*n^4-72*n^3+226*n^2-624*n+717)])/192,{n,3,20}]}] (* Vaclav Kotesovec after Heinrich Ludwig, Mar 28 2014 *)
Drop[CoefficientList[Series[-x^2 - x^2*(1 - x + 51*x^2 + 454*x^3 + 1374*x^4 + 2527*x^5 + 1990*x^6 + 634*x^7 - 347*x^8 - 49*x^9 + 87*x^10 + 16*x^11 - 20*x^12 + 3*x^13) / ((-1+x)^9*(1+x)^5), {x, 0, 20}], x],2] (* Vaclav Kotesovec, Mar 29 2014 *)
Showing 1-9 of 9 results.
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