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.

Previous Showing 21-25 of 25 results.

A129149 Permutations with exactly 7 fixed points.

Original entry on oeis.org

1, 0, 36, 240, 2970, 34848, 454740, 6362928, 95450355, 1527194240, 25962321528, 467321755680, 8879113408308, 177582268088640, 3729227629977720, 82043007859339296, 1886989180765048965, 45287740338360829056
Offset: 7

Views

Author

Zerinvary Lajos, May 25 2007

Keywords

Crossrefs

Programs

  • Maple
    a:=n->sum(n!*sum((-1)^k/(k-6)!, j=0..n), k=6..n): seq(a(n)/7!, n=6..24);
    restart: G(x):=exp(-x)/(1-x)*(x^7/7!): f[0]:=G(x): for n from 1 to 26 do f[n]:=diff(f[n-1],x) od: x:=0: seq(f[n],n=7..24); # Zerinvary Lajos, Apr 03 2009
  • Mathematica
    With[{nn=40}, Drop[CoefficientList[Series[Exp[-x]/(1 - x) x^7/7!, {x, 0, nn}], x]Range[0, nn]!, 7]] (* Vincenzo Librandi, Feb 19 2014 *)
  • PARI
    x='x+O('x^66); Vec( serlaplace(exp(-x)/(1-x)*(x^7/7!)) ) \\ Joerg Arndt, Feb 19 2014

Formula

a(n) = A008290(n,7).
E.g.f.: exp(-x)/(1-x)*(x^7/7!). [Zerinvary Lajos, Apr 03 2009]
Conjecture: (-n+7)*a(n) +n*(n-8)*a(n-1) +n*(n-1)*a(n-2)=0. - R. J. Mathar, Nov 02 2015
O.g.f.: (1/7!)*Sum_{k>=7} k!*x^k/(1 + x)^(k+1). - Ilya Gutkovskiy, Apr 15 2017
D-finite with recurrence (-n+7)*a(n) +n*(n-8)*a(n-1) +n*(n-1)*a(n-2)=0. - R. J. Mathar, Jul 06 2023

Extensions

Changed offset from 0 to 7 by Vincenzo Librandi, Feb 19 2014
Edited by Joerg Arndt, Feb 19 2014

A129153 Rencontres numbers: permutations with exactly 8 fixed points.

Original entry on oeis.org

1, 0, 45, 330, 4455, 56628, 795795, 11930490, 190900710, 3245287760, 58415223438, 1109889169740, 22197783520770, 466153453732680, 10255375982438730, 235873647595600476, 5660967542295146895, 141524188557377590800
Offset: 8

Views

Author

Zerinvary Lajos, May 25 2007

Keywords

Crossrefs

Column k=8 of A008290.

Programs

  • Maple
    a:= n-> -sum((n-1)!*sum((-1)^k/(k-7)!, j=0..n-1), k=7..n-1)/8!: seq(a(n), n=8..30);
  • Mathematica
    With[{nn=40}, Drop[CoefficientList[Series[Exp[-x]/(1 - x) x^8/8!, {x, 0, nn}], x]Range[0, nn]!, 8]] (* Vincenzo Librandi, Feb 19 2014 *)
  • PARI
    x='x+O('x^66); Vec( serlaplace(exp(-x)/(1-x)*(x^8/8!)) ) \\ Joerg Arndt, Feb 19 2014

Formula

a(n) = A008290(n,8).
E.g.f.: exp(-x)/(1-x)*(x^8/8!). [Joerg Arndt, Feb 19 2014]
O.g.f.: (1/8!)*Sum_{k>=8} k!*x^k/(1 + x)^(k+1). - Ilya Gutkovskiy, Apr 15 2017
D-finite with recurrence (-n+8)*a(n) +n*(n-9)*a(n-1) +n*(n-1)*a(n-2)=0. - R. J. Mathar, Jul 06 2023

Extensions

Changed offset from 0 to 8 by Vincenzo Librandi, Feb 19 2014

A129217 Permutations with exactly 9 fixed points.

Original entry on oeis.org

1, 0, 55, 440, 6435, 88088, 1326325, 21209760, 360590230, 6490575520, 123321027258, 2466420377200, 51794828215130, 1139486220235440, 26208183066232310, 628996393588267936, 15724909839708741375
Offset: 9

Views

Author

Zerinvary Lajos, May 25 2007

Keywords

Crossrefs

Programs

  • Maple
    a:=n->sum(n!*sum((-1)^k/(k-8)!, j=0..n), k=8..n): seq(a(n)/9!, n=8..27);
    restart: G(x):=exp(-x)/(1-x)*(x^9/9!): f[0]:=G(x): for n from 1 to 26 do f[n]:=diff(f[n-1],x) od: x:=0: seq(f[n],n=9..25); # Zerinvary Lajos, Apr 03 2009
  • Mathematica
    With[{nn=40}, Drop[CoefficientList[Series[Exp[-x]/(1 - x) x^9/9!, {x, 0, nn}], x]Range[0, nn]!, 9]] (* Vincenzo Librandi, Feb 19 2014 *)
  • PARI
    x='x+O('x^66); Vec( serlaplace(exp(-x)/(1-x)*(x^9/9!)) ) \\ Joerg Arndt, Feb 19 2014

Formula

a(n) = A008290(n,9).
E.g.f.: exp(-x)/(1-x)*(x^9/9!). [Zerinvary Lajos, Apr 03 2009]
O.g.f.: (1/9!)*Sum_{k>=9} k!*x^k/(1 + x)^(k+1). - Ilya Gutkovskiy, Apr 15 2017

Extensions

Changed offset from 0 to 9 by Vincenzo Librandi, Feb 19 2014
Edited by Joerg Arndt, Feb 19 2014

A129238 Permutations with exactly 11 fixed points.

Original entry on oeis.org

1, 0, 78, 728, 12285, 192192, 3279640, 59001696, 1121107806, 22421988160, 470862104076, 10358965584240, 238256209789598, 5718149032454208, 142953725815812600, 3716796871203401440, 100353515522504876775
Offset: 11

Views

Author

Zerinvary Lajos, May 25 2007

Keywords

Crossrefs

Programs

  • Maple
    a:=n->sum(n!*sum((-1)^k/(k-10)!, j=0..n), k=10..n): seq(a(n)/11!, n=10..27);
    restart: G(x):=exp(-x)/(1-x)*(x^11/11!): f[0]:=G(x): for n from 1 to 29 do f[n]:=diff(f[n-1],x) od: x:=0: seq(f[n],n=11..27); # Zerinvary Lajos, Apr 03 2009
  • Mathematica
    With[{nn=40}, Drop[CoefficientList[Series[Exp[-x]/(1 - x) x^11/11!, {x, 0, nn}], x]Range[0, nn]!, 11]] (* Vincenzo Librandi, Feb 19 2014 *)
  • PARI
    x='x+O('x^66); Vec( serlaplace(exp(-x)/(1-x)*(x^11/11!)) ) \\ Joerg Arndt, Feb 19 2014

Formula

a(n) = A008290(n,11).
E.g.f.: exp(-x)/(1-x)*(x^11/11!) . [Zerinvary Lajos, Apr 03 2009]
O.g.f.: (1/11!)*Sum_{k>=11} k!*x^k/(1 + x)^(k+1). - Ilya Gutkovskiy, Apr 15 2017

Extensions

Changed offset from 0 to 11 by Vincenzo Librandi, Feb 19 2014
Edited by Joerg Arndt, Feb 19 2014

A129255 Permutations with exactly 12 fixed points.

Original entry on oeis.org

1, 0, 91, 910, 16380, 272272, 4919460, 93419352, 1868513010, 39238479280, 863247190806, 19854684036460, 476512419579196, 11912810484279600, 309733072600927300, 8362792960207653240, 234158202885844712475
Offset: 12

Views

Author

Zerinvary Lajos, May 25 2007

Keywords

Crossrefs

Column k=12 of A008290.

Programs

  • Maple
    a:=n->sum(n!*sum((-1)^k/(k-11)!, j=0..n), k=11..n): seq(-a(n)/12!, n=11..28);
    restart: G(x):=exp(-x)/(1-x)*(x^12/12!): f[0]:=G(x): for n from 1 to 29 do f[n]:=diff(f[n-1],x) od: x:=0: seq(f[n],n=12..28);# Zerinvary Lajos, Apr 03 2009
  • Mathematica
    With[{nn=40}, Drop[CoefficientList[Series[Exp[-x]/(1 - x) x^12/12!, {x, 0, nn}], x]Range[0, nn]!, 12]] (* Vincenzo Librandi, Feb 19 2014 *)
  • PARI
    x='x+O('x^66); Vec( serlaplace(exp(-x)/(1-x)*(x^12/12!)) ) \\ Joerg Arndt, Feb 19 2014

Formula

E.g.f.: exp(-x)/(1-x)*(x^12/12!). [Zerinvary Lajos, Apr 03 2009]
O.g.f.: (1/12!)*Sum_{k>=12} k!*x^k/(1 + x)^(k+1). - Ilya Gutkovskiy, Apr 15 2017

Extensions

Changed offset from 0 to 12 by Vincenzo Librandi, Feb 19 2014
Edited by Joerg Arndt, Feb 19 2014
Previous Showing 21-25 of 25 results.