A201243 -id:A201243 - cp's OEIS frontend

A201861 Number of ways to place n nonattacking ferses on an n X n board.

1, 4, 38, 661, 16286, 527654, 21191208, 1015335608, 56484795166, 3576188894116, 253756155257774, 19937566770720487, 1717714713900798962, 160977153444563000938, 16300053518916522372836, 1773133639291617644092637, 206197950879511078156507433

Offset: 1

Vaclav Kotesovec, Dec 06 2011

Fers is a leaper [1,1].

V. Kotesovec, Non-attacking chess pieces, 6ed, 2013, p. 423.

Cf. A201243 - A201248, A002465, A067965.

Asymptotic (Kotesovec, 2011): a(n) ~ n^(2n)/n!*exp(-5/2).

a(15) from Vaclav Kotesovec, Jan 03 2012
a(16) from Vaclav Kotesovec, Aug 31 2016
a(17) from Vaclav Kotesovec, May 30 2021

A201244 Number of ways to place 3 non-attacking ferses on an n X n board.

Original entry on oeis.org

0, 0, 38, 340, 1630, 5552, 15210, 35828, 75530, 146240, 264702, 453620, 742918, 1171120, 1786850, 2650452, 3835730, 5431808, 7545110, 10301460, 13848302, 18357040, 24025498, 31080500, 39780570, 50418752, 63325550, 78871988, 97472790, 119589680, 145734802

Offset: 1

Vaclav Kotesovec, Nov 28 2011

Fers is a leaper [1,1].

Vincenzo Librandi, Table of n, a(n) for n = 1..1000
Vaclav Kotesovec, Non-attacking chess pieces, 6ed, p.415
Index entries for linear recurrences with constant coefficients, signature (7,-21,35,-35,21,-7,1).

Cf. A172124, A201243, A201245, A201246, A201247, A201248.

I:=[0, 0, 38, 340, 1630, 5552, 15210, 35828]; [n le 8 select I[n] else 7*Self(n-1)-21*Self(n-2)+35*Self(n-3)-35*Self(n-4)+21*Self(n-5)-7*Self(n-6)+Self(n-7): n in [1..40]]; // Vincenzo Librandi, Apr 30 2013

[0] cat [(n-2)*(n^5+2*n^4-11*n^3 +2*n^2+54*n-60)/6: n in [2..35]]; // Vincenzo Librandi, Apr 30 2013

CoefficientList[Series[- 2 x^2 (x^5 + 3 x^4 - 24 x^3 + 24 x^2 + 37 x + 19) / (x-1)^7, {x, 0, 40}], x] (* Vincenzo Librandi, Apr 30 2013 *)

a(n) = (n-2)*(n^5 + 2n^4 - 11n^3 + 2n^2 + 54n - 60)/6, n>=2.
G.f.: -2x^3*(x^5 + 3x^4 - 24x^3 + 24x^2 + 37x + 19)/(x-1)^7.
a(n) = 7*a(n-1)-21*a(n-2)+35*a(n-3)-35*a(n-4)+21*a(n-5)-7*a(n-6)+a(n-7). - Vincenzo Librandi, Apr 30 2013

A201245 Number of ways to place 4 non-attacking ferses on an n X n board.

Original entry on oeis.org

0, 0, 29, 661, 6285, 35378, 143787, 468529, 1301351, 3202970, 7170593, 14872997, 28969129, 53527866, 94568255, 160741233, 264175507, 421511954, 655152581, 994751765, 1478979173, 2157585442, 3093803379, 4367119121, 6076449375, 8343762538, 11318183177

Offset: 1

Vaclav Kotesovec, Nov 28 2011

Fers is a leaper [1,1].

Vincenzo Librandi, Table of n, a(n) for n = 1..1000
V. Kotesovec, Non-attacking chess pieces, 6ed, p.415
Index entries for linear recurrences with constant coefficients, signature (9, -36, 84, -126, 126, -84, 36, -9, 1).

Cf. A172127, A201243, A201244, A201246, A201247, A201248.

CoefficientList[Series[- x^2 (2 x^8 - 55 x^7 + 230 x^6 - 254 x^5 - 225 x^4 + 173 x^3 + 1380 x^2 + 400 x + 29)/(x-1)^9, {x, 0, 40}], x] (* Vincenzo Librandi, Apr 30 2013 *)

a(n) = (n^8 - 30n^6 + 48n^5 + 299n^4 - 912n^3 - 462n^2 + 4368n - 4200)/24, n>=3.

G.f.: -x^3*(2*x^8 - 55*x^7 + 230*x^6 - 254*x^5 - 225*x^4 + 173*x^3 + 1380*x^2 + 400*x + 29)/(x-1)^9.

A201246 Number of ways to place 5 non-attacking ferses on an n X n board.

Original entry on oeis.org

0, 0, 12, 780, 16286, 159452, 992412, 4567836, 16959488, 53617596, 149618794, 377841356, 879314442, 1911495356, 3922051616, 7657895196, 14321764860, 25791609308, 44921419134, 75946019596, 125016699158, 200899440924, 315872975684, 486869916572, 736910896536

Offset: 1

Vaclav Kotesovec, Nov 28 2011

Fers is a leaper [1,1].

Vincenzo Librandi, Table of n, a(n) for n = 1..1000
V. Kotesovec, Non-attacking chess pieces, 6ed, p.415
Index entries for linear recurrences with constant coefficients, signature (11, -55, 165, -330, 462, -462, 330, -165, 55, -11, 1).

Cf. A172129, A201243, A201244, A201245, A201247, A201248.

CoefficientList[Series[2 x^2 (11 x^11 - 135 x^10 + 549 x^9 - 993 x^8 + 1172 x^7 - 2968 x^6 + 7085 x^5 - 4715x^4 - 10613 x^3 - 4183 x^2- 324 x - 6)/(x-1)^11, {x, 0, 40}], x] (* Vincenzo Librandi, Apr 30 2013 *)

a(n) = n^10/120 - 5n^8/12 + 2n^7/3 + 191n^6/24 - 24n^5 - 661n^4/12 + 880n^3/3 - 937n^2/15 - 1176n + 1436, n>=4.

G.f.: 2x^3*(11x^11 - 135x^10 + 549x^9 - 993x^8 + 1172x^7 - 2968x^6 + 7085x^5 - 4715x^4 - 10613x^3 - 4183x^2 - 324x - 6)/(x-1)^11.

A201247 Number of ways to place 6 non-attacking ferses on an n X n board.

Original entry on oeis.org

0, 0, 2, 552, 29412, 527654, 5196928, 34528698, 173951172, 714042302, 2503447216, 7744201834, 21635290132, 55540293510, 132752090192, 298491879178, 636559136340, 1296099575166, 2533344878048, 4774975629082, 8712052571140, 15436347060646, 26634487077600

Offset: 1

Vaclav Kotesovec, Nov 28 2011

Fers is a leaper [1,1].

Vincenzo Librandi, Table of n, a(n) for n = 1..1000
V. Kotesovec, Non-attacking chess pieces, 6ed, p.415
Index entries for linear recurrences with constant coefficients, signature (13, -78, 286, -715, 1287, -1716, 1716, -1287, 715, -286, 78, -13, 1).

Cf. A176886, A201243, A201244, A201245, A201246, A201248.

CoefficientList[Series[- 2 x^2 (41 x^14 - 502 x^13 + 2506 x^12 - 7605 x^11 + 18870 x^10 - 41305 x^9 + 60117 x^8 - 21366 x^7 - 73987 x^6 + 52960 x^5 + 237560 x^4 + 93891 x^3 + 11196 x^2 + 263 x + 1)/(x-1)^13, {x, 0, 40}], x] (* Vincenzo Librandi, Apr 30 2013 *)

a(n) = n^12/720 - 5n^10/48 + n^9/6 + 461n^8/144 - 29n^7/3 - 2147n^6/48 + 1289n^5/6 + 65807n^4/360 - 6356n^3/3 + 9185n^2/6 + 22834n/3 - 11478, n>=5.

G.f.: -2x^3*(41x^14 - 502x^13 + 2506x^12 - 7605x^11 + 18870x^10 - 41305x^9 + 60117x^8 - 21366x^7 - 73987x^6 + 52960x^5 + 237560x^4 + 93891x^3 + 11196x^2 + 263x + 1)/(x-1)^13.

A201248 Number of ways to place 7 non-attacking ferses on an n X n board.

Original entry on oeis.org

0, 0, 0, 216, 38070, 1314600, 21191208, 207830308, 1442794332, 7775083960, 34530764200, 131660992164, 443702617356, 1350258600008, 3771242866680, 9789675562020, 23856321869260, 55015308882264, 120855465245464, 254284702668580, 514791197224860, 1006655249550696

Offset: 1

Vaclav Kotesovec, Nov 28 2011

nonn

Fers is a leaper [1,1].

V. Kotesovec, Non-attacking chess pieces
Index entries for linear recurrences with constant coefficients, signature (15, -105, 455, -1365, 3003, -5005, 6435, -6435, 5005, -3003, 1365, -455, 105, -15, 1).

Cf. A187239, A201243, A201244, A201245, A201246, A201247.

a(n) = n^14/5040 - n^12/48 + n^11/30 + 673n^10/720 - 17n^9/6 - 1019n^8/48 + 197n^7/2 + 9772n^6/45 - 3443n^5/2 + 47n^4/4 + 74259n^3/5 - 1816352n^2/105 - 49376n + 90660, n>=6.

G.f.: 2*x^4*(125*x^16 - 1785*x^15 + 11715*x^14 - 50121*x^13 + 158605*x^12 - 367485*x^11 + 570175*x^10 - 533381*x^9 + 460395*x^8 - 1262515*x^7 + 2731225*x^6 - 1795227*x^5 - 5484089*x^4 - 2685639*x^3 - 383115*x^2 - 17415*x - 108)/(x-1)^15.

cp's OEIS Frontend

A201861 Number of ways to place n nonattacking ferses on an n X n board.

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A201244 Number of ways to place 3 non-attacking ferses on an n X n board.

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A201245 Number of ways to place 4 non-attacking ferses on an n X n board.

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A201246 Number of ways to place 5 non-attacking ferses on an n X n board.

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A201247 Number of ways to place 6 non-attacking ferses on an n X n board.

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A201248 Number of ways to place 7 non-attacking ferses on an n X n board.

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