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 1-5 of 5 results.

A356752 E.g.f. satisfies A(x) = 1/(1 - x)^(x^2/2 * A(x)).

Original entry on oeis.org

1, 0, 0, 3, 6, 20, 360, 2394, 17220, 260280, 3076920, 35980560, 595686960, 9760411440, 159321570408, 3093987619800, 63314740616400, 1318245318411840, 30240056863978560, 736919729169603840, 18522487833889334400, 495842871278901363840, 14014346231616983128800
Offset: 0

Views

Author

Seiichi Manyama, Sep 03 2022

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 22; A[_] = 1;
    Do[A[x_] = 1/(1 - x)^(x^2/2*A[x]) + O[x]^(nmax+1) // Normal, {nmax}];
    CoefficientList[A[x], x]*Range[0, nmax]! (* Jean-François Alcover, Mar 04 2024 *)
  • PARI
    a(n) = n!*sum(k=0, n\3, (k+1)^(k-1)*abs(stirling(n-2*k, k, 1))/(2^k*(n-2*k)!));
    
  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(sum(k=0, N, (k+1)^(k-1)*(-x^2/2*log(1-x))^k/k!)))
    
  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(-lambertw(x^2/2*log(1-x)))))
    
  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(lambertw(x^2/2*log(1-x))/(x^2/2*log(1-x))))

Formula

a(n) = n! * Sum_{k=0..floor(n/3)} (k+1)^(k-1) * |Stirling1(n-2*k,k)|/(2^k * (n-2*k)!).
E.g.f.: A(x) = Sum_{k>=0} (k+1)^(k-1) * (-x^2/2 * log(1-x))^k / k!.
E.g.f.: A(x) = exp( -LambertW(x^2/2 * log(1-x)) ).
E.g.f.: A(x) = LambertW(x^2/2 * log(1-x))/(x^2/2 * log(1-x)).

A356952 E.g.f. satisfies log(A(x)) = x^3/6 * (exp(x) - 1) * A(x).

Original entry on oeis.org

1, 0, 0, 0, 4, 10, 20, 35, 1736, 15204, 88320, 415965, 7632460, 121801966, 1368227224, 12184672955, 176889193040, 3490851044360, 59703361471296, 837948141904569, 13407228541467540, 283596013866706450, 6226093732482731800, 121326684752194084471
Offset: 0

Views

Author

Seiichi Manyama, Sep 06 2022

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 23; A[_] = 1;
    Do[A[x_] = Exp[x^3/6*(Exp[x] - 1)*A[x]] + O[x]^(nmax+1) // Normal, {nmax}];
    CoefficientList[A[x], x]*Range[0, nmax]! (* Jean-François Alcover, Mar 05 2024 *)
  • PARI
    a(n) = n!*sum(k=0, n\4, (k+1)^(k-1)*stirling(n-3*k, k, 2)/(6^k*(n-3*k)!));
    
  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(sum(k=0, N, (k+1)^(k-1)*(x^3/6*(exp(x)-1))^k/k!)))
    
  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(-lambertw(x^3/6*(1-exp(x))))))
    
  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(lambertw(x^3/6*(1-exp(x)))/(x^3/6*(1-exp(x)))))

Formula

a(n) = n! * Sum_{k=0..floor(n/4)} (k+1)^(k-1) * Stirling2(n-3*k,k)/(6^k * (n-3*k)!).
E.g.f.: A(x) = Sum_{k>=0} (k+1)^(k-1) * (x^3/6 * (exp(x) - 1))^k / k!.
E.g.f.: A(x) = exp( -LambertW(x^3/6 * (1 - exp(x))) ).
E.g.f.: A(x) = LambertW(x^3/6 * (1 - exp(x)))/(x^3/6 * (1 - exp(x))).

A356968 E.g.f. satisfies A(x) = 1/(1 - x * A(x))^(x^3/6 * A(x)).

Original entry on oeis.org

1, 0, 0, 0, 4, 10, 40, 210, 4144, 40320, 409800, 4527600, 72552480, 1170449280, 19489513680, 338983444800, 6672681818880, 141166715289600, 3149324442700800, 73497460049395200, 1825098639493104000, 47984287767342796800, 1326460667797094860800
Offset: 0

Views

Author

Seiichi Manyama, Sep 06 2022

Keywords

Crossrefs

Programs

  • PARI
    a(n) = n!*sum(k=0, n\4, (n-2*k+1)^(k-1)*abs(stirling(n-3*k, k, 1))/(6^k*(n-3*k)!));

Formula

a(n) = n! * Sum_{k=0..floor(n/4)} (n-2*k+1)^(k-1) * |Stirling1(n-3*k,k)|/(6^k * (n-3*k)!).

A356913 E.g.f. satisfies A(x)^A(x) = 1/(1 - x)^(x^3/6).

Original entry on oeis.org

1, 0, 0, 0, 4, 10, 40, 210, 784, 5040, 40200, 369600, 5285280, 72072000, 1006889520, 14760345600, 210510263040, 3131345817600, 49229619129600, 818940523564800, 15054020163619200, 301204611031564800, 6455999452413772800, 146587705490513548800
Offset: 0

Views

Author

Seiichi Manyama, Sep 03 2022

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 23; A[_] = 1;
    Do[A[x_] = ((1 - x)^(-x^3/6))^(1/A[x]) + O[x]^(nmax+1) // Normal, {nmax}];
    CoefficientList[A[x], x]*Range[0, nmax]! (* Jean-François Alcover, Mar 04 2024 *)
  • PARI
    a(n) = n!*sum(k=0, n\4, (-k+1)^(k-1)*abs(stirling(n-3*k, k, 1))/(6^k*(n-3*k)!));
    
  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(sum(k=0, N, (-k+1)^(k-1)*(-x^3/6*log(1-x))^k/k!)))
    
  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(lambertw(-x^3/6*log(1-x)))))
    
  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(-x^3/6*log(1-x)/lambertw(-x^3/6*log(1-x))))

Formula

a(n) = n! * Sum_{k=0..floor(n/4)} (-k+1)^(k-1) * |Stirling1(n-3*k,k)|/(6^k * (n-3*k)!).
E.g.f.: A(x) = Sum_{k>=0} (-k+1)^(k-1) * (-x^3/6 * log(1-x))^k / k!.
E.g.f.: A(x) = exp( LambertW(-x^3/6 * log(1-x)) ).
E.g.f.: A(x) = -x^3/6 * log(1-x)/LambertW(-x^3/6 * log(1-x)).

A356925 E.g.f. satisfies A(x) = 1/(1 - x)^(exp(x) * A(x)).

Original entry on oeis.org

1, 1, 6, 51, 614, 9655, 188209, 4389532, 119363488, 3711190881, 129932611723, 5060364817200, 217054300138136, 10168837756846145, 516709033266165479, 28306732060349788908, 1663231006737554997168, 104344911495734048046929
Offset: 0

Views

Author

Seiichi Manyama, Sep 04 2022

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 20; CoefficientList[Series[LambertW[E^x * Log[1-x]]/(E^x * Log[1-x]), {x, 0, nmax}], x] * Range[0, nmax]! (* Vaclav Kotesovec, Nov 14 2022 *)
  • PARI
    my(N=20, x='x+O('x^N)); Vec(serlaplace(sum(k=0, N, (k+1)^(k-1)*(-exp(x)*log(1-x))^k/k!)))
    
  • PARI
    my(N=20, x='x+O('x^N)); Vec(serlaplace(exp(-lambertw(exp(x)*log(1-x)))))
    
  • PARI
    my(N=20, x='x+O('x^N)); Vec(serlaplace(lambertw(exp(x)*log(1-x))/(exp(x)*log(1-x))))

Formula

E.g.f.: A(x) = Sum_{k>=0} (k+1)^(k-1) * (-exp(x) * log(1-x))^k / k!.
E.g.f.: A(x) = exp( -LambertW(exp(x) * log(1-x)) ).
E.g.f.: A(x) = LambertW(exp(x) * log(1-x))/(exp(x) * log(1-x)).
a(n) ~ sqrt(1 + exp(1+r)/(1-r)) * n^(n-1) / (r^(n - 1/2) * exp(n-1)), where r = 0.249272970940807862774650581662931601739615720771408527... is the root of the equation exp(1+r) * log(1-r) = -1. - Vaclav Kotesovec, Nov 14 2022
Showing 1-5 of 5 results.