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.

A365759 G.f. satisfies A(x) = 1 + x*A(x)*(1 + x^3*A(x)^5).

Original entry on oeis.org

1, 1, 1, 1, 2, 8, 29, 85, 217, 541, 1471, 4447, 13975, 43103, 129083, 382535, 1147956, 3519462, 10947483, 34162483, 106341406, 330590764, 1030528133, 3229411337, 10170424724, 32127163822, 101633409379, 321862281571, 1020889305476, 3244779281894, 10335256815761
Offset: 0

Views

Author

Seiichi Manyama, Sep 18 2023

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=0, n\4, binomial(n-3*k, k)*binomial(n+2*k+1, n-3*k)/(n+2*k+1));

Formula

a(n) = Sum_{k=0..floor(n/4)} binomial(n-3*k,k) * binomial(n+2*k+1,n-3*k) / (n+2*k+1) = Sum_{k=0..floor(n/4)} binomial(n+2*k,6*k) * binomial(6*k,k) / (5*k+1).

A365761 G.f. satisfies A(x) = 1 + x*A(x)*(1 + x^2*A(x)^5).

Original entry on oeis.org

1, 1, 1, 2, 8, 29, 91, 289, 1009, 3706, 13606, 49822, 184726, 696052, 2648746, 10132072, 38952970, 150635860, 585724594, 2287631614, 8968247626, 35281363830, 139256375922, 551306272137, 2188516471579, 8709331962133, 34739262293455, 138863195368540
Offset: 0

Views

Author

Seiichi Manyama, Sep 18 2023

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=0, n\3, binomial(n-2*k, k)*binomial(n+3*k+1, n-2*k)/(n+3*k+1));

Formula

a(n) = Sum_{k=0..floor(n/3)} binomial(n-2*k,k) * binomial(n+3*k+1,n-2*k) / (n+3*k+1) = Sum_{k=0..floor(n/3)} binomial(n+3*k,6*k) * binomial(6*k,k) / (5*k+1).

A365758 G.f. satisfies A(x) = 1 + x*A(x) / (1 - x^4*A(x)^5).

Original entry on oeis.org

1, 1, 1, 1, 1, 2, 8, 29, 85, 212, 481, 1081, 2627, 7100, 20328, 58023, 160430, 430391, 1140892, 3051678, 8334638, 23199896, 65148939, 182781853, 510225082, 1419091293, 3948954920, 11034704856, 31001204632, 87466532564, 247303929326, 699572256145
Offset: 0

Views

Author

Seiichi Manyama, Sep 18 2023

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=0, n\4, binomial(n-3*k-1, k)*binomial(n+k+1, n-4*k)/(n+k+1));

Formula

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

A366025 Expansion of (1/x) * Series_Reversion( x*(1-x)/(1+x^5) ).

Original entry on oeis.org

1, 1, 2, 5, 14, 43, 139, 465, 1595, 5577, 19804, 71228, 258946, 950030, 3513050, 13079920, 48993149, 184490361, 698020080, 2652192675, 10115878915, 38717526745, 148655862210, 572412768275, 2209969761924, 8553073927858, 33176952295730, 128960722306128
Offset: 0

Views

Author

Seiichi Manyama, Sep 26 2023

Keywords

Crossrefs

Programs

  • Mathematica
    CoefficientList[InverseSeries[Series[x(1-x)/(1+x^5),{x,0,28}],x]/x,x] (* Stefano Spezia, Sep 26 2023 *)
  • PARI
    a(n) = sum(k=0, n\5, binomial(n-4*k, k)*binomial(2*n-5*k+1, n-4*k)/(2*n-5*k+1));
    
  • PARI
    Vec(serreverse(x*(1-x)/(1+x^5)+O(x^30))/x) \\ Michel Marcus, Sep 26 2023

Formula

G.f. satisfies A(x) = 1 + x*A(x)^2*(1 + x^4*A(x)^3).
a(n) = Sum_{k=0..floor(n/5)} binomial(n-4*k,k) * binomial(2*n-5*k+1,n-4*k)/(2*n-5*k+1) = (1/(n+1)) * Sum_{k=0..floor(n/5)} binomial(n+1,k) * binomial(2*n-5*k,n-5*k).
Showing 1-4 of 4 results.