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.

A357345 E.g.f. satisfies A(x) = -log(1 - x * exp(A(x))) * exp(3 * A(x)).

Original entry on oeis.org

0, 1, 9, 173, 5226, 216564, 11429592, 733443990, 55447217928, 4826605609584, 475490102407200, 52299789903627408, 6353202640983827472, 844774875973448667792, 122040471544637793494760, 19034141943046836097099080, 3187643959565686909679931648
Offset: 0

Views

Author

Seiichi Manyama, Sep 25 2022

Keywords

Crossrefs

Programs

  • PARI
    a(n) = sum(k=1, n, (n+3*k)^(k-1)*abs(stirling(n, k, 1)));

Formula

a(n) = Sum_{k=1..n} (n+3*k)^(k-1) * |Stirling1(n,k)|.
E.g.f.: Series_Reversion( exp(-x) * (1 - exp(-x * exp(-3*x))) ). - Seiichi Manyama, Sep 09 2024

A357333 E.g.f. satisfies A(x) = -log(1 - x) * exp(2 * A(x)).

Original entry on oeis.org

0, 1, 5, 50, 778, 16604, 451668, 14947568, 582982160, 26187136128, 1331445995520, 75589772147328, 4739901861071232, 325353447339098112, 24264683011603485696, 1953776475810372817920, 168924939633683095452672, 15609228287753846217412608
Offset: 0

Views

Author

Seiichi Manyama, Sep 24 2022

Keywords

Crossrefs

Programs

  • Mathematica
    nmax = 17; A[_] = 0;
    Do[A[x_] = -Log[1 - x]*Exp[2*A[x]] + O[x]^(nmax+1) // Normal, {nmax}];
    CoefficientList[A[x], x]*Range[0, nmax]! (* Jean-François Alcover, Mar 05 2024 *)
  • PARI
    my(N=20, x='x+O('x^N)); concat(0, Vec(serlaplace(-lambertw(2*log(1-x))/2)))
    
  • PARI
    a(n) = sum(k=1, n, (2*k)^(k-1)*abs(stirling(n, k, 1)));

Formula

E.g.f.: -LambertW(2 * log(1 - x))/2.
a(n) = Sum_{k=1..n} (2 * k)^(k-1) * |Stirling1(n,k)|.
a(n) ~ n^(n-1) / (sqrt(2) * (exp(exp(-1)/2)-1)^(n - 1/2) * exp(n - n*exp(-1)/2 - 1/2)). - Vaclav Kotesovec, Oct 04 2022
E.g.f.: Series_Reversion( 1 - exp(-x * exp(-2*x)) ). - Seiichi Manyama, Sep 09 2024

A357322 Expansion of e.g.f. -LambertW(log(1 - 3*x)/3).

Original entry on oeis.org

0, 1, 5, 45, 586, 10024, 213084, 5428072, 161475320, 5501761488, 211466328400, 9057714349672, 428022643010544, 22127292215218072, 1242503403120434168, 75319473068729478360, 4902798528238919060224, 341102498012848479889408
Offset: 0

Views

Author

Seiichi Manyama, Sep 24 2022

Keywords

Crossrefs

Programs

  • Mathematica
    With[{m = 20}, Range[0, m]! * CoefficientList[Series[-ProductLog[Log[1 - 3*x]/3], {x, 0, m}], x]] (* Amiram Eldar, Sep 24 2022 *)
  • PARI
    my(N=20, x='x+O('x^N)); concat(0, Vec(serlaplace(-lambertw(log(1-3*x)/3))))
    
  • PARI
    a(n) = sum(k=1, n, 3^(n-k)*k^(k-1)*abs(stirling(n, k, 1)));

Formula

a(n) = Sum_{k=1..n} 3^(n-k) * k^(k-1) * |Stirling1(n,k)|.
a(n) ~ 3^(n - 1/2) * n^(n-1) / ((-1 + exp(3*exp(-1)))^(n - 1/2) * exp(n - 1/2 - 3*n*exp(-1))). - Vaclav Kotesovec, Oct 04 2022
E.g.f.: Series_Reversion( (1 - exp(-3 * x * exp(-x)))/3 ). - Seiichi Manyama, Sep 11 2024

A357393 E.g.f. satisfies A(x) = -log(1 - x * exp(3 * A(x))).

Original entry on oeis.org

0, 1, 7, 110, 2730, 93024, 4037880, 213127200, 13253058000, 948964262400, 76899763100160, 6957624460550400, 695236239163065600, 76043127767523840000, 9036546669251861760000, 1159342449440429270016000, 159708538424128885551360000, 23512778013219939149561856000
Offset: 0

Views

Author

Seiichi Manyama, Sep 26 2022

Keywords

Crossrefs

Programs

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

Formula

E.g.f. satisfies A(x) = log(1 + x * exp(4 * A(x))).
a(n) = Sum_{k=1..n} (3 * n)^(k-1) * |Stirling1(n,k)|.
a(n) = Sum_{k=1..n} (4 * n)^(k-1) * Stirling1(n,k).
a(n) = Product_{k=3*n+1..4*n-1} k = (4*n-1)!/(3*n)! for n > 0.
E.g.f.: Series_Reversion( exp(-4*x) * (exp(x) - 1) ). - Seiichi Manyama, Sep 10 2024
Showing 1-4 of 4 results.