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 20 results. Next

A079908 Solution to the Dancing School Problem with 3 girls and n+3 boys: f(3,n).

Original entry on oeis.org

1, 4, 14, 36, 76, 140, 234, 364, 536, 756, 1030, 1364, 1764, 2236, 2786, 3420, 4144, 4964, 5886, 6916, 8060, 9324, 10714, 12236, 13896, 15700, 17654, 19764, 22036, 24476, 27090, 29884, 32864, 36036, 39406, 42980, 46764, 50764, 54986, 59436
Offset: 0

Views

Author

Jaap Spies, Jan 28 2003

Keywords

Comments

The Dancing School Problem: a line of g girls (g>0) with integer heights ranging from m to m+g-1 cm and a line of g+h boys (h>=0) ranging in height from m to m+g+h-1 cm are facing each other in a dancing school (m is the minimal height of both girls and boys).
A girl of height l can choose a boy of her own height or taller with a maximum of l+h cm. We call the number of possible matchings f(g,h).
This problem is equivalent to a rooks problem: The number of possible placings of g non-attacking rooks on a g X g+h chessboard with the restriction i <= j <= i+h for the placement of a rook on square (i,j): f(g,h) = per(B), the permanent of the corresponding (0,1)-matrix B, b(i, j)=1 if and only if i <= j <= i+h
f(g,h) = per(B), the permanent of the (0,1)-matrix B of size g X g+h with b(i,j)=1 if and only if i <= j <= i+h.
For fixed g, f(g,n) is polynomial in n for n >= g-2. See reference.

Crossrefs

Cf. Essentially the same as A061989.

Programs

Formula

a(n) = max(1, n^3 + 3*n), found by elementary counting.
G.f.: 1+2*x*(2-x+2*x^2)/(1-x)^4. - R. J. Mathar, Nov 19 2007

A079909 Solution to the Dancing School Problem with 4 girls and n+4 boys: f(4,n).

Original entry on oeis.org

1, 5, 26, 90, 246, 566, 1146, 2106, 3590, 5766, 8826, 12986, 18486, 25590, 34586, 45786, 59526, 76166, 96090, 119706, 147446, 179766, 217146, 260090, 309126, 364806, 427706, 498426, 577590, 665846, 763866, 872346, 992006, 1123590
Offset: 0

Views

Author

Jaap Spies, Jan 28 2003

Keywords

Comments

f(g,h) = per(B), the permanent of the (0,1)-matrix B of size g X g+h with b(i,j)=1 if and only if i <= j <= i+h. See A079908 for more information.
For fixed g, f(g,n) is polynomial in n for n >= g-2. See reference.

Crossrefs

Programs

  • PARI
    Vec(-(x^2+1)*(x^4+10*x^2+1)/(x-1)^5 + O(x^100)) \\ Colin Barker, Jan 04 2015

Formula

a(0)=1, a(1)=5, a(n)=n^4 - 2*n^3 + 9*n^2 - 8*n + 6 (n>=2) found by applying theorem 7.2.1 of Brualdi, Ryser: Combinatorial Matrix Theory.
G.f.: -(x^2+1)*(x^4+10*x^2+1) / (x-1)^5. - Colin Barker, Jan 04 2015
E.g.f.: exp(x)*(6 + 10*x^2 + 4*x^3 + x^4) - 5 - x. - Stefano Spezia, Dec 18 2019

Extensions

More terms from Benoit Cloitre, Jan 29 2003

A079910 Solution to the Dancing School Problem with 5 girls and n+5 boys: f(5,n).

Original entry on oeis.org

1, 6, 46, 212, 738, 2104, 5150, 11196, 22162, 40688, 70254, 115300, 181346, 275112, 404638, 579404, 810450, 1110496, 1494062, 1977588, 2579554, 3320600, 4223646, 5314012, 6619538, 8170704, 10000750, 12145796, 14644962, 17540488, 20877854
Offset: 0

Views

Author

Jaap Spies, Jan 28 2003

Keywords

Comments

f(g,h) = per(B), the permanent of the (0,1)-matrix B of size g X (g+h) with b(i,j)=1 if and only if i <= j <= i+h. See A079908 for more information.
For fixed g, f(g,n) is polynomial in n for n >= g-2. See reference.

Crossrefs

Programs

  • Magma
    [1,6] cat [n^5-5*n^4+25*n^3-55*n^2+80*n-46: n in [2..30]]; // Vincenzo Librandi, Feb 17 2015
  • Mathematica
    CoefficientList[Series[(6 x^7 + 11 x^6 + 20 x^5 + 51 x^4 + 6 x^3 + 25 x^2 + 1) / (x - 1)^6, {x, 0, 30}], x] (* Vincenzo Librandi, Feb 17 2015 *)
  • PARI
    Vec((6*x^7+11*x^6+20*x^5+51*x^4+6*x^3+25*x^2+1)/(x-1)^6 + O(x^100)) \\ Colin Barker, Jan 04 2015
    

Formula

a(0)=1, a(1)=6, a(2)=46, a(n) = n^5 - 5*n^4 + 25*n^3 - 55*n^2 + 80*n - 46.
G.f.: (6*x^7 + 11*x^6 + 20*x^5 + 51*x^4 + 6*x^3 + 25*x^2 + 1) / (x-1)^6. - Colin Barker, Jan 04 2015
E.g.f.: 47 + 6*x + exp(x)*(-46 + 46*x + 20*x^3 + 5*x^4 + x^5). - Stefano Spezia, Dec 18 2019

Extensions

More terms from Benoit Cloitre, Jan 29 2003

A079911 Solution to the Dancing School Problem with 6 girls and n+6 boys: f(6,n).

Original entry on oeis.org

1, 7, 79, 478, 2108, 7364, 21652, 55532, 127604, 268108, 523244, 960212, 1672972, 2788724, 4475108, 6948124, 10480772, 15412412, 22158844, 31223108, 43207004, 58823332, 78908852, 104437964, 136537108, 176499884, 225802892, 286122292
Offset: 0

Views

Author

Jaap Spies, Jan 28 2003

Keywords

Comments

f(g,h) = per(B), the permanent of the (0,1)-matrix B of size g X g+h with b(i,j)=1 if and only if i <= j <= i+h. See A079908 for more information.
For fixed g, f(g,n) is polynomial in n for n >= g-2. See reference.

Crossrefs

Programs

  • Maple
    seq(n^6-9*n^5+60*n^4-225*n^3+555*n^2-774*n+484,n=4..40);
  • Mathematica
    CoefficientList[Series[-(6 x^10 - 29 x^9 + 120 x^8 - 49 x^7 + 267 x^6 + 105 x^5 + 211 x^4 + 37 x^3 + 51 x^2 + 1)/(x - 1)^7, {x, 0, 28}], x] (* Michael De Vlieger, Dec 23 2019 *)
    LinearRecurrence[{7,-21,35,-35,21,-7,1},{1,7,79,478,2108,7364,21652,55532,127604,268108,523244},40] (* Harvey P. Dale, Jul 02 2022 *)
  • PARI
    Vec(-(6*x^10 -29*x^9 +120*x^8 -49*x^7 +267*x^6 +105*x^5 +211*x^4 +37*x^3 +51*x^2 +1) / (x -1)^7 + O(x^100)) \\ Colin Barker, Jan 04 2015

Formula

a(0)=1, a(2)=7, a(3)=79, a(n)=n^6-9*n^5+60*n^4-225*n^3+555*n^3-774*n+484.
G.f.: -(6*x^10 -29*x^9 +120*x^8 -49*x^7 +267*x^6 +105*x^5 +211*x^4 +37*x^3 +51*x^2 +1) / (x -1)^7. - Colin Barker, Jan 04 2015

A079912 Solution to the Dancing School Problem with 7 girls and n+7 boys: f(7,n).

Original entry on oeis.org

1, 8, 133, 1044, 5794, 24720, 86608, 260720, 693552, 1666000, 3675680, 7549488, 14591440, 26770832, 46955760, 79197040, 129067568, 204062160, 314062912, 471875120, 693838800, 1000520848, 1417492880, 1976199792, 2714924080
Offset: 0

Views

Author

Jaap Spies, Jan 28 2003

Keywords

Comments

f(g,h) = per(B), the permanent of the (0,1)-matrix B of size g X g+h with b(i,j)=1 if and only if i <= j <= i+h. See A079908 for more information.
For fixed g, f(g,n) is polynomial in n for n >= g-2. See reference.

Crossrefs

Programs

  • Maple
    seq(n^7-14*n^6+126*n^5-700*n^4+2625*n^3-6342*n^2+9072*n-5840,n=5..20);
  • Mathematica
    Join[{1,8,133,1044,5794},Table[n^7-14n^6+126n^5-700n^4+2625n^3- 6342n^2 +9072n-5840,{n,5,30}]] (* Harvey P. Dale, May 03 2011 *)
  • PARI
    Vec(-(46*x^12 -340*x^11 +931*x^10 -1808*x^9 +727*x^8 -1400*x^7 -1506*x^6 -656*x^5 -788*x^4 -148*x^3 -97*x^2 -1) / (x -1)^8 + O(x^100)) \\ Colin Barker, Jan 04 2015

Formula

a(0) = 1, a(1) = 8, a(2) = 133, a(3) = 1044, a(4) = 5794; for n>4, a(n) = n^7-14*n^6+126*n^5-700*n^4+2625*n^3-6342*n^2+9072*n-5840.
G.f.: -(46*x^12 -340*x^11 +931*x^10 -1808*x^9 +727*x^8 -1400*x^7 -1506*x^6 -656*x^5 -788*x^4 -148*x^3 -97*x^2 -1) / (x -1)^8. - Colin Barker, Jan 04 2015

Extensions

More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Apr 06 2003

A079926 Solution to the Dancing School Problem with n girls and n+7 boys: f(n,7).

Original entry on oeis.org

8, 57, 364, 2106, 11196, 55532, 260720, 1173240, 5112544, 21670160, 89700624, 363862092, 1450606028, 5697401802, 22088730348, 84669409935, 321307769052, 1208513572803, 4509661963752, 16709568237540
Offset: 1

Views

Author

Jaap Spies, Jan 28 2003

Keywords

Comments

f(g,h) = per(B), the permanent of the (0,1)-matrix B of size g X g+h with b(i,j)=1 if and only if i <= j <= i+h. See A079908 for more information.

Crossrefs

Extensions

Corrected by Jaap Spies, Feb 01 2004
More terms Dec 14 2006

A079913 Solution to the Dancing School Problem with 8 girls and n+8 boys: f(8,n).

Original entry on oeis.org

1, 9, 221, 2227, 15458, 80196, 334072, 1173240, 3598120, 9856552, 24553080, 56423032, 121013800, 244555560, 469343992, 860997880, 1517994792, 2583928360, 4262971000, 6839066232, 10699415080, 16362861352, 24513820920, 36042440440, 52091711272, 74112304680
Offset: 0

Views

Author

Jaap Spies, Jan 28 2003

Keywords

Comments

f(g,h) = per(B), the permanent of the (0,1)-matrix B of size g X g+h with b(i,j)=1 if and only if i <= j <= i+h. See A079908 for more information.
For fixed g, f(g,n) is polynomial in n for n >= g-2. See reference.

Crossrefs

Programs

  • Maple
    A079913 := n->n^8 -20*n^7 +238*n^6 -1820*n^5 +9625*n^4 -35000*n^3 +84448*n^2 -122240*n +80680: (1,9,221,2227,15458,80196, seq(A079913(n), n=6..30)); # edited by Wesley Ivan Hurt, Sep 17 2015
  • Mathematica
    CoefficientList[Series[-(484*x^14 - 3902*x^13 + 13791*x^12 - 25930*x^11 + 32928*x^10 - 15756*x^9 + 14443*x^8 + 8652*x^7 + 8524*x^6 + 3690*x^5 + 2741*x^4 + 478*x^3 + 176*x^2 + 1)/(x - 1)^9, {x, 0, 30}], x] (* Wesley Ivan Hurt, Sep 17 2015 *)
  • PARI
    Vec(-(484*x^14 -3902*x^13 +13791*x^12 -25930*x^11 +32928*x^10 -15756*x^9 +14443*x^8 +8652*x^7 +8524*x^6 +3690*x^5 +2741*x^4 +478*x^3 +176*x^2 +1)/(x -1)^9 + O(x^100)) \\ Colin Barker, Jan 05 2015

Formula

a(0)=1, a(1)=9, a(2)=221, a(3)=2227, a(4)=15459, a(5)=80196, for n >= 6, a(n)= n^8 -20*n^7 +238*n^6 -1820*n^5 +9625*n^4 -35000*n^3 +84448*n^2 -122240*n +80680.
G.f.: -(484*x^14 -3902*x^13 +13791*x^12 -25930*x^11 +32928*x^10 -15756*x^9 +14443*x^8 +8652*x^7 +8524*x^6 +3690*x^5 +2741*x^4 +478*x^3 +176*x^2 +1) / (x -1)^9. - Colin Barker, Jan 05 2015
a(n) = 9*a(n-1) - 36*a(n-2) + 84*a(n-3) - 126*a(n-4) + 126*a(n-5) - 84*a(n-6) + 36*a(n-7) - 9*a(n-8) + a(n-9), for n>8. - Wesley Ivan Hurt, Sep 17 2015

A079914 Solution to the Dancing School Problem with 9 girls and n+9 boys: f(9,n).

Original entry on oeis.org

1, 10, 364, 4664, 40296, 253072, 1249768, 5112544, 17990600, 56010096, 157175032, 403579328, 959942664, 2136701200, 4488418616, 8961185952, 17105944648, 31378295984, 55549351800, 95256535936, 158727963272, 257719103568
Offset: 0

Views

Author

Jaap Spies, Jan 28 2003

Keywords

Comments

f(g,h) = per(B), the permanent of the (0,1)-matrix B of size g X g+h with b(i,j)=1 if and only if i <= j <= i+h. See A079908 for more information.
For fixed g, f(g,n) is polynomial in n for n >= g-2. See reference.

Crossrefs

Programs

  • Maple
    f := n->n^9-27*n^8+414*n^7-4158*n^6+29421*n^5-148743*n^4+530796*n^3-1276992*n^2+1866384*n-1255608; seq(f(i),i=7..21);
  • Mathematica
    CoefficientList[Series[-(5840 x^16 - 52960 x^15 + 210480 x^14 - 481464 x^13 + 671100 x^12 - 619882 x^11 + 258311 x^10 - 123144 x^9 - 98197 x^8 - 57276 x^7 - 46818 x^6 - 18160 x^5 - 9046 x^4 - 1354 x^3 - 309 x^2 - 1)/(x - 1)^10, {x, 0, 21}], x] (* Michael De Vlieger, Dec 23 2019 *)
  • PARI
    Vec(-(5840*x^16 -52960*x^15 +210480*x^14 -481464*x^13 +671100*x^12 -619882*x^11 +258311*x^10 -123144*x^9 -98197*x^8 -57276*x^7 -46818*x^6 -18160*x^5 -9046*x^4 -1354*x^3 -309*x^2 -1) / (x -1)^10 + O(x^100)) \\ Colin Barker, Jan 05 2015

Formula

a(0)=1, a(1)=10, a(2)=364, a(3)=4664, a(4)=40296, a(5)=253072, a(6)=1249768, for n >= 7: a(n)=n^9-27n^8+414n^7-4158n^6+29421n^5-148743n^4+530796n^3-1276992n^2+1866384n-1255608.
G.f.: -(5840*x^16 -52960*x^15 +210480*x^14 -481464*x^13 +671100*x^12 -619882*x^11 +258311*x^10 -123144*x^9 -98197*x^8 -57276*x^7 -46818*x^6 -18160*x^5 -9046*x^4 -1354*x^3 -309*x^2 -1) / (x -1)^10.- Colin Barker, Jan 05 2015

A079915 Solution to the Dancing School Problem with 10 girls and n+10 boys: f(10,n).

Original entry on oeis.org

1, 11, 596, 9627, 103129, 780902, 4557284, 21670160, 87396728, 308055528, 971055240, 2780440664, 7324967640, 17945144328, 41249101928, 89635336440, 185317652664, 366517590440, 696695849928
Offset: 0

Views

Author

Jaap Spies, Jan 28 2003

Keywords

Comments

f(g,h) = per(B), the permanent of the (0,1)-matrix B of size g X g+h with b(i,j)=1 if and only if i <= j <= i+h. See A079908 for more information.
For fixed g, f(g,n) is polynomial in n for n >= g-2. See reference.

References

  • Jaap Spies, Dancing School Problems, Nieuw Archief voor Wiskunde 5/7 nr. 4, Dec 2006, pp. 283-285.

Crossrefs

Programs

  • Maple
    f:= n-> n^10 -35*n^9 +675*n^8 -8610*n^7 +78435*n^6 -523467*n^5 +2562525*n^4 -9008160*n^3 +21623220*n^2 -31840760*n +21750840: seq(f(i), i=8..21);

Formula

for n>=8: a(n) = n^10 -35*n^9 +675*n^8 -8610*n^7 +78435*n^6 -523467*n^5 +2562525*n^4 -9008160*n^3 +21623220*n^2 -31840760*n +21750840.

Extensions

Corrected by Jaap Spies, Feb 01 2004

A079918 Solution to the Dancing School Problem with 13 girls and n+13 boys: f(13,n).

Original entry on oeis.org

1, 14, 2567, 79544, 1596800, 20789082, 196933710, 1450606028, 8719846960, 44321202192, 195717772000, 767025716736, 2713659864832, 8787898861568
Offset: 0

Views

Author

Jaap Spies, Jan 28 2003

Keywords

Comments

f(g,h) = per(B), the permanent of the (0,1)-matrix B of size g X g+h with b(i,j)=1 if and only if i <= j <= i+h. See A079908 for more information.
For fixed g, f(g,n) is polynomial in n for n >= g-2. See reference.

References

  • Jaap Spies, Dancing School Problems, Nieuw Archief voor Wiskunde 5/7 nr. 4, Dec 2006, pp. 283-285.

Crossrefs

Extensions

Corrected by Jaap Spies, Feb 01 2004
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