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.

A360730 Expansion of Sum_{k>=0} (k * x * (1 + k*x^2))^k.

Original entry on oeis.org

1, 1, 4, 28, 272, 3368, 50768, 902397, 18481408, 428556075, 11099001600, 317544062217, 9946366838784, 338537433281448, 12441407233436672, 491002325860132371, 20710640842719301632, 929821866165431838038, 44270378887441746923520
Offset: 0

Views

Author

Seiichi Manyama, Feb 18 2023

Keywords

Crossrefs

Programs

  • PARI
    my(N=20, x='x+O('x^N)); Vec(sum(k=0, N, (k*x*(1+k*x^2))^k))
    
  • PARI
    a(n) = sum(k=0, n\3, (n-2*k)^(n-k)*binomial(n-2*k, k));

Formula

a(n) = Sum_{k=0..floor(n/3)} (n-2*k)^(n-k) * binomial(n-2*k,k).

A360728 Expansion of Sum_{k>=0} (k * x * (1 + x^3))^k.

Original entry on oeis.org

1, 1, 4, 27, 257, 3133, 46737, 824567, 16792845, 387700506, 10005766337, 285445919589, 8919587932524, 302975123887680, 11115145723728035, 438000897534309171, 18450681900124075166, 827395845674975999727, 39352977072147424071861
Offset: 0

Views

Author

Seiichi Manyama, Feb 18 2023

Keywords

Crossrefs

Programs

  • PARI
    my(N=20, x='x+O('x^N)); Vec(sum(k=0, N, (k*x*(1+x^3))^k))
    
  • PARI
    a(n) = sum(k=0, n\4, (n-3*k)^(n-3*k)*binomial(n-3*k, k));

Formula

a(n) = Sum_{k=0..floor(n/4)} (n-3*k)^(n-3*k) * binomial(n-3*k,k).

A360032 Expansion of Sum_{k>=0} (k * x * (1 + (k * x)^3))^k.

Original entry on oeis.org

1, 1, 4, 27, 257, 3189, 48843, 889079, 18730597, 447945714, 11983618199, 354519428597, 11490618543066, 404910044246256, 15412461332440829, 630199633730994675, 27548323149955792880, 1282044807268698303751, 63284535745130267484867
Offset: 0

Views

Author

Seiichi Manyama, Feb 19 2023

Keywords

Crossrefs

Programs

  • PARI
    my(N=20, x='x+O('x^N)); Vec(sum(k=0, N, (k*x*(1+(k*x)^3))^k))
    
  • PARI
    a(n) = sum(k=0, n\4, (n-3*k)^n*binomial(n-3*k, k));

Formula

a(n) = Sum_{k=0..floor(n/4)} (n-3*k)^n * binomial(n-3*k,k).

A360749 Expansion of Sum_{k>=0} (x * (1 + k*x^3))^k.

Original entry on oeis.org

1, 1, 1, 1, 2, 5, 10, 17, 30, 64, 146, 315, 649, 1386, 3164, 7381, 16931, 38649, 90406, 217474, 527586, 1277452, 3112371, 7705059, 19336789, 48800634, 123617380, 315671212, 814711955, 2119996540, 5545342621, 14584694613, 38641783669, 103158314515
Offset: 0

Views

Author

Seiichi Manyama, Feb 19 2023

Keywords

Crossrefs

Programs

  • PARI
    my(N=40, x='x+O('x^N)); Vec(sum(k=0, N, (x*(1+k*x^3))^k))
    
  • PARI
    a(n) = sum(k=0, n\4, (n-3*k)^k*binomial(n-3*k, k));

Formula

a(n) = Sum_{k=0..floor(n/4)} (n-3*k)^k * binomial(n-3*k,k).
Showing 1-4 of 4 results.