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.

A305306 Expansion of e.g.f. 1/(1 + log(1 - x)/(1 - x)).

Original entry on oeis.org

1, 1, 5, 35, 324, 3744, 51902, 839362, 15513096, 322550616, 7451677632, 189366303840, 5249764639248, 157666361452560, 5099445234111888, 176713626295062384, 6531995374500741888, 256537368987293878272, 10667901271715707803264, 468261481657502075856768, 21635865693957558515860224
Offset: 0

Views

Author

Ilya Gutkovskiy, May 29 2018

Keywords

Comments

a(n)/n! is the invert transform of [1, 1 + 1/2, 1 + 1/2 + 1/3, 1 + 1/2 + 1/3 + 1/4, ...].

Examples

			E.g.f.: A(x) = 1 + x + 5*x^2/2! + 35*x^3/3! + 324*x^4/4! + 3744*x^5/5! + 51902*x^6/6! + ...
		

Crossrefs

Programs

  • Maple
    H:= proc(n) H(n):= 1/n +`if`(n=1, 0, H(n-1)) end:
    b:= proc(n) option remember; `if`(n=0, 1,
          add(H(j)*b(n-j), j=1..n))
        end:
    a:= n-> b(n)*n!:
    seq(a(n), n=0..20);  # Alois P. Heinz, May 29 2018
  • Mathematica
    nmax = 20; CoefficientList[Series[1/(1 + Log[1 - x]/(1 - x)), {x, 0, nmax}], x] Range[0, nmax]!
    nmax = 20; CoefficientList[Series[1/(1 - Sum[HarmonicNumber[k] x^k , {k, 1, nmax}]), {x, 0, nmax}], x] Range[0, nmax]!
    a[0] = 1; a[n_] := a[n] = Sum[HarmonicNumber[k] a[n - k], {k, 1, n}]; Table[n! a[n], {n, 0, 20}]
  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(1/(1+log(1-x)/(1-x)))) \\ Seiichi Manyama, May 10 2023

Formula

E.g.f.: 1/(1 - Sum_{k>=1} (A001008(k)/A002805(k))*x^k).
a(n) ~ n! / ((1/LambertW(1)^2 - 1) * (1 - LambertW(1))^n). - Vaclav Kotesovec, Aug 08 2021
a(n) = Sum_{k=0..n} |Stirling1(n,k)| * A006153(k). - Seiichi Manyama, May 10 2023

A362911 Expansion of e.g.f. 1/( 1 - (1 + x) * log(1 + x) ).

Original entry on oeis.org

1, 1, 3, 11, 60, 384, 3062, 27838, 293416, 3447768, 45277392, 651587760, 10254900048, 174557518992, 3203361670896, 62938642659504, 1319693558377728, 29390794198726656, 693223221342879360, 17256288944072200320, 452215395177034040064
Offset: 0

Views

Author

Seiichi Manyama, May 10 2023

Keywords

Crossrefs

Programs

  • PARI
    my(N=30, x='x+O('x^N)); Vec(serlaplace(1/(1-(1+x)*log(1+x))))

Formula

a(n) = Sum_{k=0..n} Stirling1(n,k) * A006153(k).
a(n) ~ sqrt(2*Pi) * n^(n + 1/2) / ((1 + LambertW(1)) * exp(n) * (1/LambertW(1) - 1)^(n+1)). - Vaclav Kotesovec, Nov 11 2023
Showing 1-2 of 2 results.