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.

A375273 Expansion of 1/(1 - 2*x - 3*x^2 - 4*x^3 + 4*x^4).

Original entry on oeis.org

1, 2, 7, 24, 73, 238, 763, 2436, 7821, 25050, 80255, 257200, 824081, 2640582, 8461187, 27111644, 86872853, 278363058, 891946503, 2858027016, 9157854361, 29344123550, 94026132235, 301283944500, 965391362461, 3093362593162, 9911930522767, 31760378496864
Offset: 0

Views

Author

Seiichi Manyama, Aug 09 2024

Keywords

Crossrefs

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(1/(1-2*x-3*x^2-4*x^3+4*x^4))
    
  • PARI
    a(n) = sum(k=0, n\2, 2^k*binomial(2*n-2*k+2, 2*k+1))/2;

Formula

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

A375275 Expansion of (1 - x + x^2)/(1 - 2*x + 3*x^2 + 2*x^3 + x^4).

Original entry on oeis.org

1, 1, 0, -5, -13, -12, 25, 117, 196, 3, -841, -2200, -2079, 4121, 19720, 33435, 1547, -140772, -372775, -359763, 678796, 3323203, 5702319, 437200, -23557759, -63154959, -62213360, 111716475, 559940707, 972313668, 103585625, -3941367643, -10698060204
Offset: 0

Views

Author

Seiichi Manyama, Aug 09 2024

Keywords

Crossrefs

Programs

  • PARI
    my(N=40, x='x+O('x^N)); Vec((1-x+x^2)/(1-2*x+3*x^2+2*x^3+x^4))
    
  • PARI
    a(n) = sum(k=0, n\2, (-1)^k*binomial(2*n-2*k, 2*k));

Formula

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

A375288 Expansion of 1/((1 - x + x^3)^2 + 4*x^4).

Original entry on oeis.org

1, 2, 3, 2, -5, -22, -50, -74, -47, 122, 544, 1230, 1816, 1144, -3029, -13416, -30267, -44578, -27815, 75170, 330874, 744780, 1094243, 676196, -1865344, -8160100, -18326608, -26859600, -16435947, 46284926, 201243559, 450953386, 659291863, 399432970, -1148383866
Offset: 0

Views

Author

Seiichi Manyama, Aug 10 2024

Keywords

Crossrefs

Programs

  • PARI
    my(N=40, x='x+O('x^N)); Vec(1/((1-x+x^3)^2+4*x^4))
    
  • PARI
    a(n) = sum(k=0, n\3, (-1)^k*binomial(2*n-4*k+2, 2*k+1))/2;

Formula

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

A375290 Expansion of 1/((1 - x + x^4)^2 + 4*x^5).

Original entry on oeis.org

1, 2, 3, 4, 3, -4, -21, -52, -98, -144, -143, 0, 440, 1368, 2891, 4752, 5831, 3438, -7330, -33384, -81044, -148610, -211283, -197280, 39748, 732646, 2152660, 4423184, 7089816, 8360270, 4071395, -13171888, -53480919, -125422768, -224380607, -309560644, -268524883
Offset: 0

Views

Author

Seiichi Manyama, Aug 10 2024

Keywords

Crossrefs

Programs

  • PARI
    my(N=40, x='x+O('x^N)); Vec(1/((1-x+x^4)^2+4*x^5))
    
  • PARI
    a(n) = sum(k=0, n\4, (-1)^k*binomial(2*n-6*k+2, 2*k+1))/2;

Formula

a(n) = 2*a(n-1) - a(n-2) - 2*a(n-4) - 2*a(n-5) - a(n-8).
a(n) = (1/2) * Sum_{k=0..floor(n/4)} (-1)^k * binomial(2*n-6*k+2,2*k+1).
Showing 1-4 of 4 results.