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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A332915 Decimal expansion of the constant W(1) + 1/W(1), where W is Lambert's function.

Original entry on oeis.org

2, 3, 3, 0, 3, 6, 6, 1, 2, 4, 7, 6, 1, 6, 8, 0, 5, 8, 3, 2, 2, 5, 1, 7, 0, 4, 3, 9, 1, 6, 2, 0, 6, 2, 6, 3, 0, 1, 8, 9, 8, 3, 3, 7, 7, 3, 8, 5, 3, 9, 8, 6, 1, 4, 2, 7, 0, 5, 5, 8, 7, 9, 8, 4, 7, 7, 0, 3, 2, 1, 6, 4, 0, 2, 7, 3, 6, 8, 0, 3, 0, 3, 4, 8, 2, 3, 0
Offset: 1

Views

Author

Martin Renner, Mar 02 2020

Keywords

Comments

The graph of the exponential function exp(x) moved to the right by W(1) + 1/W(1) touches the graph of the natural logarithm log(x) at point (x,y) = (1/W(1), W(1)) = (A030797, A030178).

Examples

			2.33036612476168058322517043916206263018983377385398...
		

Crossrefs

Programs

  • Maple
    evalf[200](LambertW(1) + 1/LambertW(1));
  • Mathematica
    RealDigits[N[LambertW[1] + 1/LambertW[1], 120]][[1]] (* Vaclav Kotesovec, Mar 02 2020 *)
  • PARI
    my(x=lambertw(1)); x+1/x \\ Michel Marcus, Mar 02 2020

Formula

Equals 2 + Integral_{x=0..1} W(x) dx. - Amiram Eldar, Jul 18 2021

A352771 Decimal expansion of the unique real solution to exp(x) = 1/x - 1.

Original entry on oeis.org

4, 0, 1, 0, 5, 8, 1, 3, 7, 5, 4, 1, 5, 4, 7, 0, 3, 5, 6, 5, 0, 6, 2, 5, 3, 7, 5, 0, 0, 6, 4, 5, 6, 6, 2, 9, 0, 9, 5, 6, 0, 6, 9, 8, 6, 5, 0, 4, 5, 9, 7, 7, 7, 6, 3, 6, 9, 5, 9, 6, 4, 9, 2, 0, 7, 7, 8, 6, 9, 6, 3, 9, 9, 5, 4, 5, 7, 9, 6, 9, 9, 9, 5, 3, 3, 2, 5, 8, 1, 7, 1, 2, 9, 0, 8, 6, 2, 7, 6, 7, 4, 4, 4, 3, 0
Offset: 0

Views

Author

Amiram Eldar, Apr 02 2022

Keywords

Examples

			0.40105813754154703565062537500645662909560698650459...
		

References

  • István Mező, The Lambert W Function, Its Generalizations and Applications, CRC Press, 2022.

Crossrefs

Programs

  • Mathematica
    RealDigits[x /. FindRoot[Exp[x] == 1/x - 1, {x, 1}, WorkingPrecision -> 120]][[1]]
  • PARI
    solve(x=0.1, 1, exp(x) - 1/x + 1) \\ Michel Marcus, Apr 02 2022

Formula

Equals W_1(1), where W_1(x) is the 1-Lambert function.
Equals 1/2 + Sum_{n>=2} (Sum_{k=1..n-1} ((n+k-1)!/(n-1)!) * Stirling2(n-1,k)*(-1/2)^k)/(2^n*n!).
Both formulas are from Mező and Baricz (2017).
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