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 1-4 of 4 results.

A172532 Number of ways to place 5 nonattacking knights on an n X n toroidal board.

Original entry on oeis.org

0, 0, 0, 128, 120, 30312, 283906, 1872064, 8643186, 31702920, 98179400, 267487920, 659015500, 1496908840, 3179369070, 6382030592, 12207535134, 22396355496, 39617305308, 67860021680
Offset: 1

Views

Author

Vaclav Kotesovec, Feb 06 2010

Keywords

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[- 2 x^3 (648 x^16 - 10328 x^15 + 71820 x^14 - 295572 x^13 + 818512 x^12 - 1640088 x^11 + 2492742 x^10 - 2967118 x^9 + 2825821 x^8 - 2185007 x^7 + 1376780 x^6 - 677852 x^5 + 219349 x^4 - 32023 x^3 + 18016 x^2 - 644 x + 64) / (x - 1)^11, {x, 0, 50}], x] (* Vincenzo Librandi, May 29 2013 *)

Formula

a(n) = n^2*(n^8 - 90*n^6 + 3395*n^4 - 64290*n^2 + 522504)/120, n>=10.
G.f.: -2*x^4*(648*x^16-10328*x^15+71820*x^14-295572*x^13+818512*x^12-1640088*x^11+2492742*x^10-2967118*x^9+2825821*x^8-2185007*x^7+1376780*x^6-677852*x^5+219349*x^4-32023*x^3+18016*x^2-644*x+64)/(x-1)^11. - Vaclav Kotesovec, Mar 25 2010

A172533 Number of ways to place 6 nonattacking knights on an n X n toroidal board.

Original entry on oeis.org

0, 0, 0, 56, 0, 54972, 764596, 8972896, 62560728, 322246800, 1323868260, 4595943336, 14000143196, 38413461800, 96746410800, 226834407552, 500492572112, 1048044384360, 2096986629308, 4031211268200
Offset: 1

Views

Author

Vaclav Kotesovec, Feb 06 2010

Keywords

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[4 x^3 (240 x^21 - 3120 x^20 + 20470 x^19 - 105106 x^18 + 512024 x^17 - 2216597 x^16 + 7650408 x^15 - 20251702 x^14 + 41149629 x^13 - 64905350 x^12 + 80399423 x^11 - 78967736 x^10 + 61875645 x^9 - 38631940 x^8 + 19002633 x^7 - 7392461 x^6 + 2560624 x^5 - 840251 x^4 - 8486 x^3 - 14835 x^2 + 182 x - 14) / (x - 1)^13,{x, 0, 50}], x] (* Vincenzo Librandi, May 29 2013 *)

Formula

a(n) = n^2*(n^10-135n^8+8005n^6-262665n^4+4816354n^2-39858840)/720, n>=13.
G.f.: 4*x^4*(240*x^21-3120*x^20+20470*x^19-105106*x^18+512024*x^17-2216597*x^16+7650408*x^15-20251702*x^14+41149629*x^13-64905350*x^12+80399423*x^11-78967736*x^10+61875645*x^9-38631940*x^8+19002633*x^7-7392461*x^6+2560624*x^5-840251*x^4-8486*x^3-14835*x^2+182*x-14)/(x-1)^13. - Vaclav Kotesovec, Mar 25 2010

A172966 Number of ways to place 4 nonattacking knights on an n X n cylindrical board.

Original entry on oeis.org

0, 0, 0, 306, 2365, 19047, 90503, 328324, 981693, 2547955, 5933257, 12681288, 25284363, 47595023, 85357395, 146879312, 243867873, 392452803, 614423653, 938708560, 1403123967, 2056426383, 2960698943, 4194107208, 5854060325
Offset: 1

Views

Author

Vaclav Kotesovec, Feb 06 2010

Keywords

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[x^3 (76 x^13 - 684 x^12 + 2856 x^11 - 7714 x^10 + 16164 x^9 - 29151 x^8 + 45506 x^7 - 57766 x^6 + 55629 x^5 - 39385 x^4 + 21484 x^3 - 8778 x^2 + 389 x - 306) / (x - 1)^9, {x, 0, 50}], x] (* Vincenzo Librandi, May 29 2013 *)

Formula

a(n) = n*(n^7-54n^5+72n^4+1115n^3-2616n^2-8502n+26712)/24, n>=9.
G.f.: x^4*(76*x^13-684*x^12+2856*x^11-7714*x^10+16164*x^9-29151*x^8+45506*x^7-57766*x^6+55629*x^5-39385*x^4+21484*x^3-8778*x^2+389*x-306)/(x-1)^9. - Vaclav Kotesovec, Mar 25 2010

Extensions

More terms from Vincenzo Librandi, May 29 2013

A173436 Number of ways to place 7 nonattacking knights on an n X n toroidal board.

Original entry on oeis.org

0, 0, 0, 16, 0, 80352, 1359288, 31404480, 339256836, 2527519400, 14053530964, 63100177488, 240356217660, 803630856504, 2416671974700, 6655251717376, 17015566051020, 40822003107000, 92679987456312, 200490192134800
Offset: 1

Views

Author

Vaclav Kotesovec, Feb 18 2010

Keywords

Crossrefs

Programs

  • Mathematica
    CoefficientList[Series[- 4 x^3 (2535 x^24 - 61497 x^23 + 627330 x^22 - 3849410 x^21 + 16791330 x^20 - 58053150 x^19 + 170691269 x^18 - 438580125 x^17 + 976505385 x^16 - 1844050487 x^15 + 2900976825 x^14 - 3760563305 x^13 + 3991133690 x^12 - 3450574470 x^11 + 2418714751 x^10 - 1370750375 x^9 + 628081926 x^8 - 228075638 x^7 + 56855445 x^6 - 6423333 x^5 + 4868490 x^4 + 36682 x^3 + 20508 x^2 - 60 x + 4) / (x - 1)^15, {x, 0, 50}], x] (* Vincenzo Librandi, May 30 2013 *)

Formula

Explicit formula: a(n) = n^2*(n^12-189n^10+16135n^8-801255n^6+24595984n^4-445931556n^2+3756080880)/5040, n>=14. For any fixed value of k > 1, a(n) = n^(2k)/k! - 9n^(2k-2)/2/(k-2)! + (243k+143)*n^(2k-4)/24/(k-3)! - ...
G.f.: -4*x^4 * (2535*x^24 -61497*x^23 +627330*x^22 -3849410*x^21 +16791330*x^20 -58053150*x^19 +170691269*x^18 -438580125*x^17 +976505385*x^16 -1844050487*x^15 +2900976825*x^14 -3760563305*x^13 +3991133690*x^12 -3450574470*x^11 +2418714751*x^10 -1370750375*x^9 +628081926*x^8 -228075638*x^7 +56855445*x^6 -6423333*x^5 +4868490*x^4 +36682*x^3 +20508*x^2 -60*x +4) / (x-1)^15. [Vaclav Kotesovec, Mar 25 2010]
Showing 1-4 of 4 results.