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 1-3 of 3 results.

A354018 Expansion of e.g.f. -log(1-x)/(1 + log(1-x) - log(1-x)^2).

Original entry on oeis.org

0, 1, 3, 20, 172, 1864, 24248, 368136, 6388128, 124711944, 2705241672, 64550432352, 1680280323984, 47383464508080, 1438986494794704, 46821994627363968, 1625069178022566528, 59927028756823323648, 2339899614887520358656, 96439023491479275172608
Offset: 0

Views

Author

Seiichi Manyama, May 14 2022

Keywords

Crossrefs

Programs

  • Mathematica
    Table[Sum[k! * Fibonacci[k] * Abs[StirlingS1[n,k]], {k,0,n}], {n,0,20}] (* Vaclav Kotesovec, May 15 2022 *)
    With[{nn=20},CoefficientList[Series[-Log[1-x]/(1+Log[1-x]-Log[1-x]^2),{x,0,nn}],x] Range[0,nn]!] (* Harvey P. Dale, Nov 22 2024 *)
  • PARI
    my(N=20, x='x+O('x^N)); concat(0, Vec(serlaplace(-log(1-x)/(1+log(1-x)-log(1-x)^2))))
    
  • PARI
    a(n) = sum(k=0, n, k!*fibonacci(k)*abs(stirling(n, k, 1)));

Formula

a(n) = Sum_{k=0..n} k! * Fibonacci(k) * |Stirling1(n,k)|.
a(n) ~ n! * (sqrt(5) - 1) / (2 * sqrt(5) * exp((sqrt(5) - 1)/2) * (1 - exp((1 - sqrt(5))/2))^(n+1)). - Vaclav Kotesovec, May 15 2022

A358031 Expansion of e.g.f. (1 - log(1-x))/(1 + log(1-x) * (1 - log(1-x))).

Original entry on oeis.org

1, 2, 8, 52, 450, 4878, 63474, 963744, 16724016, 326497632, 7082393136, 168995017200, 4399028766192, 124051494462816, 3767315220903072, 122581568808533760, 4254486275273419008, 156890997080103149568, 6125936704495619486976, 252480641031903073955328
Offset: 0

Views

Author

Seiichi Manyama, Oct 25 2022

Keywords

Crossrefs

Programs

  • Maple
    f:= proc(n) local k; add(k!*combinat:-fibonacci(k+2)*abs(Stirling1(n,k)),k=0..n) end proc:
    map(f, [$0..30]); # Robert Israel, Oct 25 2022
  • Mathematica
    With[{nn=20},CoefficientList[Series[(1-Log[1-x])/(1+Log[1-x](1-Log[1-x])),{x,0,nn}],x] Range[ 0,nn]!] (* Harvey P. Dale, Jan 25 2024 *)
  • PARI
    my(N=20, x='x+O('x^N)); Vec(serlaplace((1-log(1-x))/(1+log(1-x)*(1-log(1-x)))))
    
  • PARI
    a(n) = sum(k=0, n, k!*fibonacci(k+2)*abs(stirling(n, k, 1)));

Formula

a(n) = Sum_{k=0..n} k! * Fibonacci(k+2) * |Stirling1(n,k)|.
a(n) = A354013(n) + A354018(n).

A354015 Expansion of e.g.f. 1/(1 - x)^(1 - log(1-x)).

Original entry on oeis.org

1, 1, 4, 18, 106, 750, 6188, 58184, 613156, 7149780, 91319712, 1267089912, 18969355656, 304646227704, 5222700792528, 95169251327040, 1836450816902928, 37403582826055824, 801728489886598848, 18037821249349491360, 424970923585819603872, 10462258547232790348512
Offset: 0

Views

Author

Seiichi Manyama, May 14 2022

Keywords

Crossrefs

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(1/(1-x)^(1-log(1-x))))
    
  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(exp(-log(1-x)*(1-log(1-x)))))
    
  • PARI
    a_vector(n) = my(v=vector(n+1)); v[1]=1; for(i=1, n, v[i+1]=(i-1)!*sum(j=1, i, (1+2*sum(k=1, j-1, 1/k))*v[i-j+1]/(i-j)!)); v;
    
  • PARI
    a(n) = sum(k=0, n, k!*sum(j=0, k\2, 1/(j!*(k-2*j)!))*abs(stirling(n, k, 1)));

Formula

E.g.f.: exp( -log(1-x) * (1 - log(1-x)) ).
a(0) = 1; a(n) = Sum_{k=1..n} A000776(k-1) * binomial(n-1,k-1) * a(n-k) = (n-1)! * Sum_{k=1..n} (1 + 2*Sum_{j=1..k-1} 1/j) * a(n-k)/(n-k)!.
a(n) = Sum_{k=0..n} A047974(k) * |Stirling1(n,k)|.
Showing 1-3 of 3 results.