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.

A382536 Expansion of 1/(1 - x*(1 + 4*x)^(3/2)).

Original entry on oeis.org

1, 1, 7, 19, 63, 221, 679, 2365, 7499, 25351, 82043, 274031, 892263, 2972127, 9686899, 32261819, 105124711, 350277365, 1140610399, 3803874525, 12372800403, 41319077557, 134176480535, 448958154449, 1454582791283, 4879992151217, 15762304059447, 53067612190093
Offset: 0

Views

Author

Seiichi Manyama, Mar 31 2025

Keywords

Comments

a(62) is negative.

Crossrefs

Programs

  • Magma
    R := PowerSeriesRing(Rationals(), 40); f := 1/(1 - x*(1 + 4*x)^(3/2)); seq := [ Coefficient(f, n) : n in [0..30] ]; seq; // Vincenzo Librandi, Apr 01 2025
  • Mathematica
    Table[Sum[4^(n-k)*Binomial[3*k/2,n-k],{k,0,n}],{n,0,35}] (* Vincenzo Librandi, Apr 01 2025 *)
  • PARI
    a(n) = sum(k=0, n, 4^(n-k)*binomial(3*k/2, n-k));
    

Formula

a(n) = Sum_{k=0..n} 4^(n-k) * binomial(3*k/2,n-k).
D-finite with recurrence (-n+1)*a(n) +2*(-2*n+7)*a(n-1) +(n-1)*a(n-2) +2*(8*n-13)*a(n-3) +24*(4*n-9)*a(n-4) +32*(8*n-23)*a(n-5) +128*(2*n-7)*a(n-6)=0. - R. J. Mathar, Apr 02 2025
a(n) ~ 3 * (-1)^(n+1) * 2^(2*n-4) / (sqrt(Pi) * n^(5/2)). - Vaclav Kotesovec, Apr 13 2025

A382515 Expansion of 1/(1 - x/(1 - 4*x)^(5/2)).

Original entry on oeis.org

1, 1, 11, 91, 691, 5101, 37323, 272405, 1987047, 14493479, 105718071, 771148119, 5625136651, 41032826127, 299316769887, 2183389173811, 15926906427179, 116180104751925, 847485191674867, 6182049517420133, 45095462188117951, 328952511222499589, 2399570809473795931
Offset: 0

Views

Author

Seiichi Manyama, Mar 30 2025

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Sum[4^(n-k)*Binomial[n+3*k/2-1,n-k],{k,0,n}],{n,0,25}] (* Vincenzo Librandi, Mar 30 2025 *)
  • PARI
    a(n) = sum(k=0, n, 4^(n-k)*binomial(n+3*k/2-1, n-k));

Formula

a(n) = Sum_{k=0..n} 4^(n-k) * binomial(n+3*k/2-1,n-k).
D-finite with recurrence (-n+1)*a(n) +2*(12*n-19)*a(n-1) +(-239*n+519)*a(n-2) +2*(638*n-1751)*a(n-3) +1280*(-3*n+10)*a(n-4) +512*(12*n-47)*a(n-5) +2048*(-2*n+9)*a(n-6)=0. - R. J. Mathar, Mar 31 2025

A382542 Expansion of 1/(1 - x/(1 - 4*x)^(3/2))^3.

Original entry on oeis.org

1, 3, 24, 172, 1191, 8091, 54214, 359274, 2358945, 15365815, 99399132, 639081780, 4086689187, 26006041209, 164767882902, 1039787209898, 6537976304109, 40973438195025, 255998969164612, 1594973077037136, 9911483124031335, 61443351455986359, 380044418794190118
Offset: 0

Views

Author

Seiichi Manyama, Mar 31 2025

Keywords

Crossrefs

Programs

  • Magma
    R:=PowerSeriesRing(Rationals(), 25); Coefficients(R!( 1/(1 - x/(1 - 4*x)^(3/2))^3)); // Vincenzo Librandi, May 12 2025
  • Mathematica
    Table[Sum[(4)^(n-k)* Binomial[k+2,2]*Binomial[n+k/2-1, n-k],{k,0,n}],{n,0,25}] (* Vincenzo Librandi, May 12 2025 *)
  • PARI
    a(n) = sum(k=0, n, 4^(n-k)*binomial(k+2, 2)*binomial(n+k/2-1, n-k));
    

Formula

a(n) = Sum_{k=0..n} 4^(n-k) * binomial(k+2,2) * binomial(n+k/2-1,n-k).
D-finite with recurrence (1951*n-648)*(n-1)*a(n) +2*(-19507*n^2+55239*n-42212)*a(n-1) +(310113*n^2-1357025*n+1557754)*a(n-2) +2*(-616231*n^2+3607803*n-5547102)*a(n-3) +4*(616138*n^2-4491203*n+8306122)*a(n-4) -256*(3899*n-16903)*(2*n-9)*a(n-5)=0. - R. J. Mathar, Apr 02 2025

A382541 Expansion of 1/(1 - x/(1 - 4*x)^(3/2))^2.

Original entry on oeis.org

1, 2, 15, 100, 645, 4098, 25795, 161256, 1002513, 6203434, 38230951, 234774948, 1437193101, 8773022374, 53416562787, 324488659784, 1967025910873, 11901070329414, 71878009609591, 433411746865948, 2609477469570885, 15689257525890666, 94208451895149123
Offset: 0

Views

Author

Seiichi Manyama, Mar 31 2025

Keywords

Crossrefs

Programs

  • Magma
    R:=PowerSeriesRing(Rationals(), 25); Coefficients(R!( 1/(1 - x/(1-4*x)^(3/2))^2)); // Vincenzo Librandi, May 12 2025
  • Mathematica
    Table[Sum[(4)^(n-k)* (k+1)* Binomial[n+k/2-1,n-k],{k,0,n}],{n,0,30}] (* Vincenzo Librandi, May 12 2025 *)
  • PARI
    a(n) = sum(k=0, n, 4^(n-k)*(k+1)*binomial(n+k/2-1, n-k));
    

Formula

a(n) = Sum_{k=0..n} 4^(n-k) * (k+1) * binomial(n+k/2-1,n-k).
D-finite with recurrence (-n+1)*a(n) +2*(8*n-13)*a(n-1) +(-95*n+217)*a(n-2) +2*(126*n-359)*a(n-3) +128*(-2*n+7)*a(n-4)=0. - R. J. Mathar, Apr 02 2025
Showing 1-4 of 4 results.