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 1-8 of 8 results.

A017847 Expansion of 1/(1 - x^6 - x^7).

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 2, 1, 0, 0, 0, 1, 3, 3, 1, 0, 0, 1, 4, 6, 4, 1, 0, 1, 5, 10, 10, 5, 1, 1, 6, 15, 20, 15, 6, 2, 7, 21, 35, 35, 21, 8, 9, 28, 56, 70, 56, 29, 17, 37, 84, 126, 126, 85, 46, 54, 121, 210, 252, 211, 131, 100, 175, 331, 462, 463, 342, 231, 275, 506, 793, 925
Offset: 0

Views

Author

Keywords

Comments

Number of compositions of n into parts 6 and 7. - Joerg Arndt, Jun 27 2013

Crossrefs

Column k=6 of A306713.

Programs

  • Magma
    m:=70; R:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/(1-x^6-x^7))); // Vincenzo Librandi, Jun 27 2013
    
  • Magma
    I:=[1,0,0,0,0,0,1]; [n le 7 select I[n] else Self(n-6)+Self(n-7): n in [1..70]]; // Vincenzo Librandi, Jun 27 2013
  • Mathematica
    CoefficientList[Series[1/(1-x^6-x^7), {x, 0, 70}], x] (* or *)  LinearRecurrence[{0, 0, 0, 0, 0, 1, 1}, {1, 0, 0, 0, 0, 0, 1}, 70] (* Harvey P. Dale, Dec 15 2012 *)
    CoefficientList[Series[1 / (1 - Total[x^Range[6, 7]]),{x, 0, 70}], x] (* Vincenzo Librandi, Jun 27 2013 *)

Formula

a(0)=1, a(1)=0,a(2)=0, a(3)=0, a(4)=0, a(5)=0, a(6)=1; for n>6, a(n) = a(n-6)+a(n-7). - Harvey P. Dale, Dec 15 2012
a(n) = Sum_{k=0..floor(n/6)} binomial(k,n-6*k). - Seiichi Manyama, Oct 01 2024

A017877 Expansion of 1/(1 - x^9 - x^10).

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 1, 2, 1, 0, 0, 0, 0, 0, 0, 1, 3, 3, 1, 0, 0, 0, 0, 0, 1, 4, 6, 4, 1, 0, 0, 0, 0, 1, 5, 10, 10, 5, 1, 0, 0, 0, 1, 6, 15, 20, 15, 6, 1, 0, 0, 1, 7, 21, 35, 35, 21, 7, 1, 0, 1, 8, 28, 56
Offset: 0

Views

Author

Keywords

Comments

Number of compositions (ordered partitions) of n into parts 9 and 10. - Ilya Gutkovskiy, May 27 2017

Crossrefs

Programs

  • Magma
    m:=80; R:=PowerSeriesRing(Integers(), m);
    Coefficients(R!(1/(1-x^9-x^10))); // Vincenzo Librandi, Jul 01 2013
    
  • Mathematica
    CoefficientList[Series[1 / (1 - Total[x^Range[9, 10]]), {x, 0, 80}], x] (* Vincenzo Librandi, Jul 01 2013 *)
  • SageMath
    def A017877_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( 1/(1-x^9-x^(10)) ).list()
    A017877_list(85) # G. C. Greubel, Sep 25 2024

Formula

a(n) = a(n-9) + a(n-10) for n > 9. - Vincenzo Librandi, Jul 01 2013
a(n) = Sum_{k=0..floor(n/9)} binomial(k,n-9*k). - Seiichi Manyama, Oct 01 2024

A017887 Expansion of 1/(1 - x^10 - x^11).

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 1, 0, 0, 0, 0, 0, 0, 0, 1, 3, 3, 1, 0, 0, 0, 0, 0, 0, 1, 4, 6, 4, 1, 0, 0, 0, 0, 0, 1, 5, 10, 10, 5, 1, 0, 0, 0, 0, 1, 6, 15, 20, 15, 6, 1, 0, 0, 0, 1, 7, 21, 35, 35, 21, 7, 1
Offset: 0

Views

Author

Keywords

Comments

Number of compositions (ordered partitions) of n into parts 10 and 11. - Ilya Gutkovskiy, May 27 2017

Crossrefs

Programs

  • Magma
    m:=80; R:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/(1-x^10-x^11))); // Vincenzo Librandi, Jul 01 2013
    
  • Magma
    I:=[1,0,0,0,0,0,0,0,0,0,1]; [n le 11 select I[n] else Self(n-10)+Self(n-11): n in [1..80]]; // Vincenzo Librandi, Jul 01 2013
    
  • Mathematica
    CoefficientList[Series[1 / (1 - Total[x^Range[10, 11]]), {x, 0, 70}], x] (* Vincenzo Librandi, Jul 01 2013 *)
    LinearRecurrence[{0,0,0,0,0,0,0,0,0,1,1},{1,0,0,0,0,0,0,0,0,0,1},100] (* Harvey P. Dale, Feb 04 2015 *)
  • SageMath
    def A017887_list(prec):
        P. = PowerSeriesRing(ZZ, prec)
        return P( 1/(1-x^10-x^(11)) ).list()
    A017887_list(100) # G. C. Greubel, Sep 25 2024

Formula

a(n) = a(n-10) + a(n-11) for n > 10. - Vincenzo Librandi, Jul 01 2013
a(n) = Sum_{k=0..floor(n/10)} binomial(k,n-10*k). - Seiichi Manyama, Oct 01 2024

A017837 Expansion of 1/(1 - x^5 - x^6).

Original entry on oeis.org

1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 1, 2, 1, 0, 0, 1, 3, 3, 1, 0, 1, 4, 6, 4, 1, 1, 5, 10, 10, 5, 2, 6, 15, 20, 15, 7, 8, 21, 35, 35, 22, 15, 29, 56, 70, 57, 37, 44, 85, 126, 127, 94, 81, 129, 211, 253, 221, 175, 210, 340, 464, 474, 396, 385, 550, 804, 938, 870, 781, 935, 1354, 1742, 1808, 1651, 1716, 2289, 3096
Offset: 0

Views

Author

Keywords

Comments

Number of compositions of n into parts 5 and 6. - Joerg Arndt, Jun 27 2013

Crossrefs

Column 5 of A306713.
Cf. A099132.

Programs

  • Magma
    m:=70; R:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/(1-x^5-x^6))); // Vincenzo Librandi, Jun 27 2013
    
  • Magma
    I:=[1,0,0,0,0,1]; [n le 6 select I[n] else Self(n-5)+Self(n-6): n in [1..70]]; // Vincenzo Librandi, Jun 27 2013
  • Mathematica
    CoefficientList[Series[1 / (1 - Total[x^Range[5, 6]]), {x, 0, 50}], x] (* Vincenzo Librandi Jun 27 2013 *)
  • PARI
    Vec(1/(1-x^5-x^6)+O(x^99)) \\ Charles R Greathouse IV, Sep 26 2012
    

Formula

a(n) = a(n-6) + a(n-5). - Jon E. Schoenfield, Aug 07 2006

A306646 Square array A(n,k), n >= 0, k >= 1, read by antidiagonals, where column k is the expansion of g.f. (k+1-x^k)/(1-x^k-x^(k+1)).

Original entry on oeis.org

2, 3, 1, 4, 0, 3, 5, 0, 2, 4, 6, 0, 0, 3, 7, 7, 0, 0, 3, 2, 11, 8, 0, 0, 0, 4, 5, 18, 9, 0, 0, 0, 4, 0, 5, 29, 10, 0, 0, 0, 0, 5, 3, 7, 47, 11, 0, 0, 0, 0, 5, 0, 7, 10, 76, 12, 0, 0, 0, 0, 0, 6, 0, 4, 12, 123, 13, 0, 0, 0, 0, 0, 6, 0, 4, 3, 17, 199
Offset: 0

Views

Author

Seiichi Manyama, Mar 03 2019

Keywords

Examples

			A(6,1) = 6*Sum_{j=1..6} binomial(j,6-j)/j = 6*(1/3+3/2+1+1/6) = 18.
A(6,2) = 6*Sum_{j=1..3} binomial(j,6-2*j)/j = 6*(1/2+1/3) = 5.
Square array begins:
    2,  3, 4, 5, 6, 7, 8, 9, 10, 11, ...
    1,  0, 0, 0, 0, 0, 0, 0,  0,  0, ...
    3,  2, 0, 0, 0, 0, 0, 0,  0,  0, ...
    4,  3, 3, 0, 0, 0, 0, 0,  0,  0, ...
    7,  2, 4, 4, 0, 0, 0, 0,  0,  0, ...
   11,  5, 0, 5, 5, 0, 0, 0,  0,  0, ...
   18,  5, 3, 0, 6, 6, 0, 0,  0,  0, ...
   29,  7, 7, 0, 0, 7, 7, 0,  0,  0, ...
   47, 10, 4, 4, 0, 0, 8, 8,  0,  0, ...
   76, 12, 3, 9, 0, 0, 0, 9,  9,  0, ...
		

Crossrefs

Programs

  • Mathematica
    T[0, k_] := k + 1; T[n_, k_] := n *Sum[Binomial[j, n - k*j]/j, {j, 1, Floor[n/k]}]; Table[T[k, n - k + 1], {n, 0, 11}, {k, 0, n}] // Flatten (* Amiram Eldar, Jun 21 2021 *)

Formula

A(0,k) = k+1 and A(n,k) = n*Sum_{j=1..floor(n/k)} binomial(j,n-k*j)/j for n > 0.
A(n,k) = (k+1)*A306713(n,k) - A306713(n-k,k) for n >= k.

A306680 Square array A(n,k), n >= 0, k >= 0, read by antidiagonals, where column k is the expansion of g.f. ((1-x)^(k-1))/((1-x)^k-x^(k+1)).

Original entry on oeis.org

1, 1, 2, 1, 1, 3, 1, 1, 2, 4, 1, 1, 1, 3, 5, 1, 1, 1, 2, 5, 6, 1, 1, 1, 1, 4, 8, 7, 1, 1, 1, 1, 2, 7, 13, 8, 1, 1, 1, 1, 1, 5, 12, 21, 9, 1, 1, 1, 1, 1, 2, 11, 21, 34, 10, 1, 1, 1, 1, 1, 1, 6, 21, 37, 55, 11, 1, 1, 1, 1, 1, 1, 2, 16, 37, 65, 89, 12
Offset: 0

Views

Author

Seiichi Manyama, Mar 05 2019

Keywords

Examples

			A(4,1) = A306713(4,1) = 5, A(4,2) = A306713(8,2) = 4.
Square array begins:
   1,  1,  1,  1,  1,  1, 1, 1, 1, ...
   2,  1,  1,  1,  1,  1, 1, 1, 1, ...
   3,  2,  1,  1,  1,  1, 1, 1, 1, ...
   4,  3,  2,  1,  1,  1, 1, 1, 1, ...
   5,  5,  4,  2,  1,  1, 1, 1, 1, ...
   6,  8,  7,  5,  2,  1, 1, 1, 1, ...
   7, 13, 12, 11,  6,  2, 1, 1, 1, ...
   8, 21, 21, 21, 16,  7, 2, 1, 1, ...
   9, 34, 37, 37, 36, 22, 8, 2, 1, ...
		

Crossrefs

Columns 0-9 give A000027(n+1), A000045(n+1), A005251(n+1), A003522, A005676, A099132, A293169, A306721, A306752, A306753.

Programs

  • Mathematica
    T[n_, k_] := Sum[Binomial[n - j, k*j], {j, 0, n}]; Table[T[k, n - k], {n, 0, 11}, {k, 0, n}] // Flatten (* Amiram Eldar, Jun 21 2021 *)

Formula

A(n,k) = Sum_{j=0..n} binomial(n-j,k*j).
A(n,k) = A306713(k*n,k) for k > 0.

A017857 Expansion of 1/(1 - x^7 - x^8).

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 1, 2, 1, 0, 0, 0, 0, 1, 3, 3, 1, 0, 0, 0, 1, 4, 6, 4, 1, 0, 0, 1, 5, 10, 10, 5, 1, 0, 1, 6, 15, 20, 15, 6, 1, 1, 7, 21, 35, 35, 21, 7, 2, 8, 28, 56, 70, 56, 28, 9, 10, 36, 84, 126, 126, 84, 37
Offset: 0

Views

Author

Keywords

Comments

Number of compositions of n into parts 7 and 8. - Joerg Arndt, Jun 28 2013

Crossrefs

Column k=7 of A306713.

Programs

  • Magma
    m:=70; R:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/(1-x^7-x^8))); // Vincenzo Librandi, Jun 28 2013
    
  • Magma
    I:=[1,0,0,0,0,0,0,1]; [n le 8 select I[n] else Self(n-7)+Self(n-8): n in [1..70]]; // Vincenzo Librandi, Jun 28 2013
    
  • Mathematica
    CoefficientList[Series[1 / (1 - Total[x^Range[7, 8]]), {x, 0, 70}], x] (* Vincenzo Librandi, Jun 28 2013 *)
    LinearRecurrence[{0,0,0,0,0,0,1,1},{1,0,0,0,0,0,0,1},80] (* Harvey P. Dale, Mar 19 2019 *)
  • PARI
    x='x+O('x^66); Vec(1/(1-x^7-x^8)) \\ Altug Alkan, Oct 07 2018

Formula

a(n) = a(n-7) + a(n-8) for n > 7. - Vincenzo Librandi, Jun 28 2013
a(n) = Sum_{k=0..floor(n/7)} binomial(k,n-7*k). - Seiichi Manyama, Oct 01 2024

A017867 Expansion of 1/(1 - x^8 - x^9).

Original entry on oeis.org

1, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 0, 0, 1, 2, 1, 0, 0, 0, 0, 0, 1, 3, 3, 1, 0, 0, 0, 0, 1, 4, 6, 4, 1, 0, 0, 0, 1, 5, 10, 10, 5, 1, 0, 0, 1, 6, 15, 20, 15, 6, 1, 0, 1, 7, 21, 35, 35, 21, 7, 1, 1, 8, 28, 56, 70, 56, 28, 8, 2, 9
Offset: 0

Views

Author

Keywords

Comments

Number of compositions of n into parts 8 and 9. - Joerg Arndt, Jun 29 2013

Crossrefs

Column k=8 of A306713.

Programs

  • Magma
    m:=80; R:=PowerSeriesRing(Integers(), m); Coefficients(R!(1/(1-x^8-x^9))); // Vincenzo Librandi, Jun 28 2013
    
  • Magma
    I:=[1,0,0,0,0,0,0,0,1]; [n le 9 select I[n] else Self(n-8)+Self(n-9): n in [1..80]]; // Vincenzo Librandi, Jun 28 2013
    
  • Mathematica
    CoefficientList[Series[1 / (1 - Total[x^Range[8, 9]]), {x, 0, 80}], x] (* Vincenzo Librandi, Jun 28 2013 *)
  • PARI
    x='x+O('x^66); Vec(1/(1-x^8-x^9)) \\ Altug Alkan, Oct 07 2018

Formula

a(n) = a(n-8) + a(n-9) for n>8. - Vincenzo Librandi, Jun 28 2013
a(n) = Sum_{k=0..floor(n/8)} binomial(k,n-8*k). - Seiichi Manyama, Oct 01 2024
Showing 1-8 of 8 results.