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.

Previous Showing 11-14 of 14 results.

A360548 E.g.f. satisfies A(x) = x * exp( 2*(x + A(x)) ).

Original entry on oeis.org

0, 1, 8, 96, 1792, 46080, 1511424, 60325888, 2837970944, 153778913280, 9432255692800, 646039266656256, 48874810528235520, 4047655951598092288, 364221261622538141696, 35384754572803304325120, 3691411033400626898796544, 411569264258973944034361344
Offset: 0

Views

Author

Seiichi Manyama, Feb 11 2023

Keywords

Crossrefs

Programs

  • Maple
    A360548 := proc(n)
        add((2*k)^(n-1)*binomial(n,k),k=1..n) ;
    end proc:
    seq(A360548(n),n=0..60) ; # R. J. Mathar, Mar 12 2023
  • PARI
    my(N=20, x='x+O('x^N)); concat(0, Vec(serlaplace(-lambertw(-2*x*exp(2*x))/2)))
    
  • PARI
    a(n) = sum(k=1, n, (2*k)^(n-1)*binomial(n, k));

Formula

E.g.f.: A(x) = (-1/2) * LambertW(-2*x * exp(2*x)).
a(n) = Sum_{k=1..n} (2*k)^(n-1) * binomial(n,k) = 4^(n-1) * A100526(n).
a(n) ~ sqrt(1 + LambertW(exp(-1))) * 2^(n-1) * n^(n-1) / (LambertW(exp(-1))^n * exp(n)). - Vaclav Kotesovec, Feb 17 2023

A360545 E.g.f. satisfies A(x) = x * exp( 3*(x + A(x))/2 ).

Original entry on oeis.org

0, 1, 6, 54, 756, 14580, 358668, 10736712, 378823392, 15395255280, 708217959600, 36380741745744, 2064234271203360, 128214974795177088, 8652900673357097472, 630483717450225530880, 49330027417316557012992, 4124992361928178722764544
Offset: 0

Views

Author

Seiichi Manyama, Feb 11 2023

Keywords

Crossrefs

Programs

  • PARI
    my(N=20, x='x+O('x^N)); concat(0, Vec(serlaplace(-2*lambertw(-3*x/2*exp(3*x/2))/3)))
    
  • PARI
    a(n) = sum(k=1, n, (3*k/2)^(n-1)*binomial(n, k));

Formula

E.g.f.: A(x) = (-2/3) * LambertW(-3*x/2 * exp(3*x/2)).
a(n) = Sum_{k=1..n} (3*k/2)^(n-1) * binomial(n,k) = 3^(n-1) * A100526(n).
a(n) ~ sqrt(1 + LambertW(exp(-1))) * 3^(n-1) * n^(n-1) / (2^(n-1) * exp(n) * LambertW(exp(-1))^n). - Vaclav Kotesovec, Feb 17 2023

A216858 Number of connected functions from {1,2,...,n} into a subset of {1,2,...,n} summed over all subsets.

Original entry on oeis.org

0, 1, 5, 38, 422, 6184, 112632, 2453296, 62202800, 1799623296, 58507176320, 2111633645824, 83777729991936, 3624054557443072, 169759643117603840, 8560585769442662400, 462387289560368764928, 26633435981686107701248, 1629609677806398679646208, 105555926477075661655441408, 7215930505311133152120995840
Offset: 0

Views

Author

Geoffrey Critzer, Sep 17 2012

Keywords

Crossrefs

Programs

  • Mathematica
    nn=20; a=-ProductLog[-x Exp[x] ]; Range[0,nn]! CoefficientList[Series[Log[1/(1-a)], {x,0,nn}], x]
  • PARI
    x='x+O('x^30); concat([0], Vec(serlaplace(log(1/(1+ lambertw(-x*exp(x))))))) \\ G. C. Greubel, Nov 16 2017

Formula

E.g.f.: log(1/(1-T(x*exp(x)))) where T(x) is the e.g.f. for A000169.
a(n) ~ n!/(2*n*LambertW(exp(-1))^n) * (1 - sqrt(2*(1 + LambertW(exp(-1))) /(Pi*n))/3). - Vaclav Kotesovec, Sep 24 2013

A360433 E.g.f. satisfies A(x) = x * exp(A(x) + x^3).

Original entry on oeis.org

0, 1, 2, 9, 88, 865, 11016, 173929, 3227792, 69010785, 1670970160, 45198840841, 1350754588008, 44196732194641, 1571453132115608, 60331412278617705, 2487385479819549856, 109608035124514365121, 5140910415583354887648, 255708987797133857518345
Offset: 0

Views

Author

Seiichi Manyama, Feb 07 2023

Keywords

Crossrefs

Programs

  • PARI
    my(N=20, x='x+O('x^N)); concat(0, Vec(serlaplace(-lambertw(-x*exp(x^3)))))

Formula

E.g.f.: -LambertW( -x*exp(x^3) ).
a(n) ~ sqrt(1+LambertW(3*exp(-3))) * 3^(n/3) * n^(n-1) / (exp(n) * (LambertW(3*exp(-3)))^(n/3)). - Vaclav Kotesovec, Feb 07 2023
Previous Showing 11-14 of 14 results.