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.

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A230284 Denominators to Dirichlet inverse of Euler totient based version of series expansion for x/LambertW(x).

Original entry on oeis.org

1, 1, 2, 3, 8, 15, 144, 35, 5760, 315, 5600, 693, 43545600, 1001, 6706022400, 6435, 14014, 109395, 376610217984000, 46189, 128047474114560000, 323323, 2540395, 2028117, 26976017466662584320000, 96577, 3241475864250624, 35102025, 2126818694000, 5386025
Offset: 1

Views

Author

Mats Granvik, Oct 15 2013

Keywords

Crossrefs

Cf. A191898, A177885, A230283 (numerators).
Similar to but strictly different from A264235.

Programs

  • Mathematica
    Clear[nn, n, k, s, x]; nn = 22; Denominator[CoefficientList[1 + Integrate[1 + Expand[Sum[Exp[Limit[Zeta[s]*Sum[(If[n == 1, 0, Table[DivisorSum[m, # MoebiusMu[#] &], {m, nn}][[GCD[n, k]]]])/(k)^(s - 1), {k, 1, n}], s -> 1]]*(-x)^n, {n, 1, nn}]], x], x]]

A264234 Numerators of the coefficients in the expansion of 1/W(x) - 1/x where W(x) is the Lambert W function.

Original entry on oeis.org

1, -1, 2, -9, 32, -625, 324, -117649, 131072, -4782969, 1562500, -25937424601, 35831808, -23298085122481, 110730297608, -4805419921875, 562949953421312, -48661191875666868481, 91507169819844, -104127350297911241532841, 640000000000000000, -865405750887126927009
Offset: 0

Views

Author

Peter Luschny, Nov 09 2015

Keywords

Comments

If prefixed by an additional 1, numerators of coefficients of expansion of exp(W(x)). - N. J. A. Sloane, Jan 08 2021

Examples

			Coefficients of expansion of exp(W(x)) are 1, 1, -1/2, 2/3, -9/8, 32/15, -625/144, 324/35, -117649/5760, 131072/2835, -4782969/44800, ... - _N. J. A. Sloane_, Jan 08 2021
		

Crossrefs

Denominators in A264235.
Cf. A036505.

Programs

  • Magma
    [(-1)^n * Numerator(n^n/Factorial(n)): n in [0..50]]; // G. C. Greubel, Nov 14 2017
  • Maple
    seq(numer((-1)^n*n^n/n!), n = 0..21);
  • Mathematica
    CoefficientList[Series[1/ProductLog[x] - 1/x, {x, 0, 21}], x] // Numerator
  • PARI
    vector(22, n, n--; (-1)^n*numerator(n^n/n!)) \\ Altug Alkan, Nov 09 2015
    

Formula

a(n) = (-1)^n*numerator(g(n)) where g(n) = n^n/n!.
a(n) = (-1)^n*denominator(h(n)) where h(n) = Sum_{k=0..n-1}(n!*n^k)/(k!*n^n).
Showing 1-2 of 2 results.