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 1-6 of 6 results.

A371044 E.g.f. satisfies A(x) = 1 + x^3*exp(x*A(x)).

Original entry on oeis.org

1, 0, 0, 6, 24, 60, 120, 5250, 80976, 726264, 4839120, 86487390, 2283242280, 42585905076, 590667519624, 10115535833130, 286758920451360, 8128299117822960, 186279550983756576, 4123388294626654134, 118916807955913504440, 4102548791571529697580
Offset: 0

Views

Author

Seiichi Manyama, Mar 09 2024

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 20; CoefficientList[Series[1 - LambertW[-E^x*x^4]/x, {x, 0, nmax}], x] * Range[0, nmax]! (* Vaclav Kotesovec, Mar 10 2024 *)
  • PARI
    a(n) = n!*sum(k=0, n\3, k^(n-3*k)*binomial(n-3*k+1, k)/((n-3*k+1)*(n-3*k)!));

Formula

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

A371018 Expansion of e.g.f. (1/x) * Series_Reversion( x/(1 + x^2*exp(x)) ).

Original entry on oeis.org

1, 0, 2, 6, 60, 620, 7950, 129402, 2365496, 50512968, 1208642490, 32223422990, 947694971652, 30435132773916, 1061061668979494, 39889366397571810, 1608910488000292080, 69305890226183224592, 3175519952912430375666, 154216789672147809137046
Offset: 0

Views

Author

Seiichi Manyama, Mar 08 2024

Keywords

Crossrefs

Programs

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

Formula

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

A372019 G.f. A(x) satisfies A(x) = ( 1 + 9*x*A(x)/(1 - x*A(x)) )^(1/3).

Original entry on oeis.org

1, 3, 3, 3, 30, 57, 84, 867, 1893, 3162, 33132, 76953, 136812, 1446204, 3478764, 6420387, 68260134, 167946159, 317782524, 3392340186, 8479140510, 16332164868, 174873206424, 442212416121, 863222622780, 9264327739716, 23637757714788, 46624054987452
Offset: 0

Views

Author

Seiichi Manyama, Apr 15 2024

Keywords

Crossrefs

Programs

  • Maple
    A371019 := proc(n)
        add(9^k*binomial((n+1)/3,k)*binomial(n-1,k-1),k=0..n) ;
        %/(n+1) ;
    end proc:
    seq(A371019(n),n=0..60) ; # R. J. Mathar, Apr 22 2024
  • PARI
    a(n) = sum(k=0, n, 9^k*binomial(n/3+1/3, k)*binomial(n-1, n-k))/(n+1);

Formula

a(n) = (1/(n+1)) * Sum_{k=0..n} 9^k * binomial(n/3+1/3,k) * binomial(n-1,n-k).
D-finite with recurrence n*(n-1)*(n+1)*a(n) -8*(2*n-5)*(8*n^2-40*n+57)*a(n-3) +4096*(n-5)*(n-6)*(n-4)*a(n-6)=0. - R. J. Mathar, Apr 22 2024

A371045 E.g.f. satisfies A(x) = 1 + x^3*A(x)*exp(x*A(x)).

Original entry on oeis.org

1, 0, 0, 6, 24, 60, 840, 15330, 161616, 1572984, 29031120, 636008670, 11426850600, 210095235636, 5137568918664, 139255673359530, 3574532174656800, 95923063388359920, 2974073508961556256, 98747639807081454774, 3287535337205171488440
Offset: 0

Views

Author

Seiichi Manyama, Mar 09 2024

Keywords

Crossrefs

Programs

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

Formula

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

A371046 E.g.f. satisfies A(x) = 1 + x^3*A(x)^2*exp(x*A(x)).

Original entry on oeis.org

1, 0, 0, 6, 24, 60, 1560, 25410, 242256, 3508344, 85882320, 1724406750, 32784999720, 839182482996, 24162605028744, 659439484706730, 19415319297457440, 658935736181053680, 23245444335085544736, 835819877947421773494, 32462532011236141677240
Offset: 0

Views

Author

Seiichi Manyama, Mar 09 2024

Keywords

Crossrefs

Programs

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

Formula

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

A371021 Expansion of e.g.f. (1/x) * Series_Reversion( x/(1 + x^3/6*exp(x)) ).

Original entry on oeis.org

1, 0, 0, 1, 4, 10, 80, 1015, 9016, 80724, 1092120, 16872405, 246966940, 3932454526, 73869476044, 1485097614455, 30688224287280, 682450482838440, 16508839426673136, 420562937260614249, 11193327347979937140, 315276822746559147250, 9383980947735649740100
Offset: 0

Views

Author

Seiichi Manyama, Mar 08 2024

Keywords

Crossrefs

Programs

  • Mathematica
    Join[{1}, Table[(n!/(n + 1))*Sum[k^(n - 3*k)*Binomial[n + 1, k]/(6^k*(n - 3*k)!), {k, 0, Floor[n/3]}], {n, 30}]] (* Wesley Ivan Hurt, Aug 05 2025 *)
  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(serreverse(x/(1+x^3/6*exp(x)))/x))
    
  • PARI
    a(n) = n!*sum(k=0, n\3, k^(n-3*k)*binomial(n+1, k)/(6^k*(n-3*k)!))/(n+1);

Formula

a(n) = (n!/(n+1)) * Sum_{k=0..floor(n/3)} k^(n-3*k) * binomial(n+1,k)/(6^k * (n-3*k)!).
Showing 1-6 of 6 results.