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 1-2 of 2 results.

A184949 E.g.f. satisfies A(x) = (1-x*A(x))^(-x*A(x)).

Original entry on oeis.org

1, 0, 2, 3, 68, 390, 8334, 98280, 2321136, 42895440, 1167767640, 29323831680, 926869947816, 29169311371200, 1064023191882000, 39974978077332480, 1664929964612590080, 72388846850592384000, 3402723408460217089344, 167636144501378081280000, 8796533195129444799189120
Offset: 0

Views

Author

Vladimir Kruchinin, Feb 03 2011

Keywords

Crossrefs

Cf. A371147.

Programs

  • Maple
    with(combinat):
    a := n-> n! * add((n+1)^(k-1)*abs(stirling1(n-k,k))/(n-k)!, k=0..n):
    seq(a(n), n=0..20);
  • Mathematica
    a[n_] := n! * Sum[(n+1)^(k-1)*Abs[StirlingS1[n-k, k]]/(n-k)!, {k, 0, n}]; Table [a[n], {n, 0, 20}] (* Jean-François Alcover, Apr 21 2015, from formula *)

Formula

a(n) = n! * sum(k=0..n, (n+1)^(k-1)*abs(stirling1(n-k,k))/(n-k)!).
a(n) ~ s*(1-r*s) * n^(n-1) / (sqrt(1 - r*s*(2-r*s)*(1-r*s)) * exp(n) * r^n), where r = 0.35521237986941340511033292... and s = 1.49319771092171695325266171... are roots of the system of equations s = (1-r*s)^(-r*s), r*s*(r*s+(-1+r*s)*log(1-r*s)) = 1-r*s. - Vaclav Kotesovec, May 03 2015
E.g.f.: (1/x) * Series_Reversion( x*(1 - x)^x ). - Seiichi Manyama, Sep 21 2024

Extensions

Edited by Alois P. Heinz, Feb 03 2011

A376350 E.g.f. satisfies A(x) = 1/(1 - x^2*A(x)^2)^(x*A(x)).

Original entry on oeis.org

1, 0, 0, 6, 0, 60, 2520, 1680, 181440, 6138720, 18295200, 1444988160, 46443196800, 357015859200, 25016537145600, 818965321574400, 12259854032025600, 815066633667686400, 28461465853402982400, 691667282863484928000, 45198900807076912896000, 1739192274792359202816000, 60318174486002275287244800
Offset: 0

Views

Author

Seiichi Manyama, Sep 21 2024

Keywords

Crossrefs

Programs

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

Formula

E.g.f.: (1/x) * Series_Reversion( x*(1 - x^2)^x ).
a(n) = n! * Sum_{k=0..floor(n/2)} (n+1)^(n-2*k-1) * |Stirling1(k,n-2*k)|/k!.
Showing 1-2 of 2 results.