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.

A099240 Main diagonal of A099239.

Original entry on oeis.org

1, 2, 8, 41, 250, 1757, 13917, 122166, 1173662, 12222605, 136927351, 1639768418, 20880556880, 281460326864, 4000651782511, 59761935358025, 935445106491702, 15303039199768237, 261030618751031385, 4632889302298054713
Offset: 0

Views

Author

Paul Barry, Oct 08 2004

Keywords

Crossrefs

Cf. A099239.

Programs

  • Magma
    [1] cat [(&+[Binomial(n+(n-1)*(j+1), n*(j+1)-1): j in [0..n]]): n in [1..30]]; // G. C. Greubel, Mar 09 2021
  • Mathematica
    Table[Sum[Binomial[n^2 -(n-1)*(j-1), j], {j,0,n}], {n,0,30}] (* G. C. Greubel, Mar 09 2021 *)
  • Sage
    [sum(binomial(n^2 -(n-1)*(j-1), j) for j in (0..n)) for n in (0..30)] # G. C. Greubel, Mar 09 2021
    

Formula

a(n) = Sum_{j=0..n} binomial(n^2 - (n-1)*(j-1), j).
a(n) = Sum_{j=0..n} binomial(n + (n-1)*(j+1), n*(j+1) - 1) with a(0) = 1.

A099241 Sums of antidiagonals of A099239.

Original entry on oeis.org

1, 2, 4, 9, 22, 57, 155, 441, 1311, 4066, 13130, 44046, 153144, 550706, 2044248, 7819897, 30779570, 124487688, 516723174, 2198726181, 9581247648, 42717268934, 194688593966, 906331074605, 4306472500778, 20871165469241, 103106015116437
Offset: 0

Views

Author

Paul Barry, Oct 08 2004

Keywords

Crossrefs

Cf. A099239.

Programs

  • Magma
    A099239:= func< n,k | (&+[Binomial(k*(n-k) -(k-1)*(j-1), j): j in [0..n-k]]) >;
    [(&+[A099239(n,j): j in [0..n]]): n in [0..30]]; // G. C. Greubel, Mar 09 2021
  • Mathematica
    A099239[n_, k_]:= Sum[Binomial[k*(n-k) -(k-1)*(j-1), j], {j,0,n-k}];
    Table[Sum[A099239[n, k], {k,0,n}], {n,0,30}] (* G. C. Greubel, Mar 09 2021 *)
  • Sage
    def A099239(n,k): return sum(binomial(k*(n-k)-(k-1)*(j-1), j) for j in (0..n-k))
    [sum(A099239(n,k) for k in (0..n)) for n in (0..30)] # G. C. Greubel, Mar 09 2021
    

Formula

a(n) = Sum_{k=0..n} Sum_{j=0..n-k} binomial(k*(n-k) - (k-1)*(j-1), j).

A099253 (7*n+6)-th terms of expansion of 1/(1-x-x^7).

Original entry on oeis.org

1, 8, 43, 211, 1030, 5055, 24851, 122166, 600470, 2951330, 14505951, 71297834, 350434385, 1722411860, 8465785506, 41609980404, 204516223418, 1005212819668, 4940697593195, 24283905085013, 119357243593561, 586649945651116
Offset: 0

Views

Author

Paul Barry, Oct 08 2004

Keywords

Crossrefs

Cf. A099239.

Programs

  • Magma
    [(&+[Binomial(7*n-6*j+6,j): j in [0..n]]): n in [0..30]]; // G. C. Greubel, Mar 09 2021
  • Mathematica
    Table[Sum[Binomial[7*n-6*(j-1), j], {j,0,n}], {n,0,30}] (* G. C. Greubel, Mar 09 2021 *)
  • Sage
    [sum(binomial(7*n-6*j+6,j) for j in (0..n)) for n in (0..30)] # G. C. Greubel, Mar 09 2021
    

Formula

G.f.: 1/((1-x)^7 - x);
Equals A099239(n, 7).
a(n) = 8*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).
a(n) = Sum_{k=0..n} binomial(7*n - 6*(k-1), k).
a(n) = Sum_{k=0..n} binomial(n + 6*(k+1), k + 6*(k+1)).
a(n) = Sum_{k=0..n} binomial(n + 6*(k+1), n-k).

A099242 (6n+5)-th terms of expansion of 1/(1 - x - x^6).

Original entry on oeis.org

1, 7, 34, 153, 686, 3088, 13917, 62721, 282646, 1273690, 5739647, 25864698, 116554700, 525233175, 2366870474, 10665883415, 48063918336, 216591552484, 976031547888, 4398313653120, 19820223058176, 89316331907533
Offset: 0

Views

Author

Paul Barry, Oct 08 2004

Keywords

Comments

A row of A099239.
Equals INVERT transform of A000389, C(n,5). [Gary W. Adamson, Feb 02 2009]

Crossrefs

Cf. A000389.

Programs

  • Mathematica
    CoefficientList[Series[1/((1 - x)^6 - x), {x, 0, 50}], x] (* G. C. Greubel, Nov 24 2017 *)
    LinearRecurrence[{7,-15,20,-15,6,-1},{1,7,34,153,686,3088},30] (* Harvey P. Dale, May 06 2018 *)
  • PARI
    my(x='x+O('x^50)); Vec(1/((1-x)^6-x)) \\ G. C. Greubel, Nov 24 2017

Formula

G.f.: 1/((1-x)^6-x).
a(n) = 7*a(n-1) - 15*a(n-2) + 20*a(n-3) - 15*a(n-4) + 6*a(n-5) - a(n-6).
a(n) = Sum_{k=0..n} binomial(6*n-5*(k-1), k).
a(n) = Sum_{k=0..n} binomial(n+5*(k+1), k+5*(k+1)).
a(n) = Sum_{k=0..n} binomial(n+5*(k+1), n-k).
Showing 1-4 of 4 results.