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 1-5 of 5 results.

A246849 Decimal expansion of 1-delta_0, where delta_0 is the Hall-Montgomery constant (A143301).

Original entry on oeis.org

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

Views

Author

Jean-François Alcover, Sep 05 2014

Keywords

Comments

This constant, by coincidence, is also a limiting probability concerning the number of cycles of a given length in a random permutation.
One has P_1(xi) = 1-delta_0 = Pi^2/6 - log(xi) - log(xi)^2 - 2*Li_2(xi), where xi = 1/(1+sqrt(e)) (see A246848 and the references).

Examples

			0.82849950685846393413956002844478789037773709577...
		

Crossrefs

Programs

  • Mathematica
    Pi^2/6 + Log[1 + Sqrt[E]] - Log[1 + Sqrt[E]]^2 - 2*PolyLog[2, 1/(1 + Sqrt[E])] // RealDigits[#, 10, 101]& // First
  • PARI
    Pi^2/6 + log(exp(1/2)+1) - log(exp(1/2)+1)^2 - 2*polylog(2, 1/(exp(1/2)+1)) \\ Charles R Greathouse IV, Sep 08 2014
    
  • Python
    from mpmath import mp, log, exp, polylog, pi
    mp.dps=102
    print([int(n) for n in list(str(pi**2/6 + log(exp(1/2)+1) - log(exp(1/2)+1)**2 - 2*polylog(2, 1/(exp(1/2)+1)))[2:-1])]) # Indranil Ghosh, Jul 04 2017

Formula

Pi^2/6 + log(1 + sqrt(e)) - log(1 + sqrt(e))^2 - 2*Li_2(1/(1 + sqrt(e))), where Li_2 is the dilogarithm function.

A126689 Decimal expansion of negative of Granville-Soundararajan constant.

Original entry on oeis.org

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

Views

Author

Jonathan Vos Post, Feb 14 2007

Keywords

Comments

For any completely multiplicative function f(n) with -1 <= f(n) <= 1, the sum f(1) + f(2) + ... + f(x) is at most (c + o(1))x, where c is this constant. Further, this bound is sharp in that for any c0 > c there are infinitely many f and arbitrarily large x giving a sum less than c0*x. - Charles R Greathouse IV, May 26 2015
Named after the British mathematician Andrew James Granville (b. 1962) and the Indian-American mathematician Kannan Soundararajan (b. 1973). - Amiram Eldar, Jun 23 2021

Examples

			-0.65699901371692786827912005688957578075547419154089...
		

References

  • Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, section 2.33, p. 206.

Crossrefs

Cf. A143301.

Programs

  • Maple
    Digits := 40 ; K := proc(s) 0.5+add( binomial(s,k)*(-1)^k/k*(exp(0.5*k)-1),k=1..s) ; end: A126689 := proc(smax) 1.0-log(4.0)+add(K(s)*2^(2-s)/s,s=1..smax) ; end: for smax from 0 to 2*Digits do print(A126689(smax)) ; od ; # R. J. Mathar, Feb 16 2007
    read("transforms3") ; Digits := 120 : x := 1+Pi^2/3+4*dilog(exp(1/2)+1) ; x := evalf(x) ; CONSTTOLIST(x) ; # R. J. Mathar, Sep 20 2009
  • Mathematica
    RealDigits[ N[ 4*PolyLog[2, -Sqrt[E]] + Pi^2/3 + 1, 105]][[1]] (* Jean-François Alcover, Nov 08 2012, after R. J. Mathar *)
  • PARI
    1-2*log(1+exp(1/2))+4*intnum(t=1,exp(1/2),log(t)/(t+1)) \\ Charles R Greathouse IV, Apr 29 2013
    
  • Python
    from mpmath import mp, polylog, sqrt, e, pi
    mp.dps=106
    print([int(k) for k in list(str(4*polylog(2, -sqrt(e)) + pi**2/3 + 1)[3:-1])]) # Indranil Ghosh, Jul 03 2017

Formula

Equals 1-2*log[1+sqrt e]+4*Integral_{t=1..sqrt e}([log t]/(1+t)) dt = 1-log 4+4*Sum_{s>=1} K(s)/(s*2^s) where K(s)=Sum_{k=0..s} binomial(s,k)*(-1)^k*[exp(k/2)-1]/k. - R. J. Mathar, Feb 16 2007
Equals 1 - 2 * A143301. - Amiram Eldar, Aug 25 2020

Extensions

More terms from R. J. Mathar, Feb 16 2007, Sep 20 2009

A246848 Decimal expansion of 1/(1+sqrt(e)), a constant appearing in the computation of a limiting probability concerning the number of cycles of a given length in a random permutation.

Original entry on oeis.org

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

Views

Author

Jean-François Alcover, Sep 05 2014

Keywords

Comments

1/(1+sqrt(e)) is the value of x that maximizes the expression Pi^2/6 - log(x) - log(x)^2 - 2*Li_2(x), where Li_2 is the dilogarithm function.

Examples

			0.37754066879814543536109943425449152124672063469108983694...
		

Crossrefs

Programs

  • Mathematica
    RealDigits[1/(1 + Sqrt[E]), 10, 101] // First
  • PARI
    1/(1+sqrt(exp(1))) \\ Michel Marcus, Sep 05 2014

A248080 Decimal expansion of P_0(xi), the maximum limiting probability that a random n-permutation has no cycle exceeding a given length.

Original entry on oeis.org

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

Views

Author

Jean-François Alcover, Oct 14 2014

Keywords

Examples

			0.098711754480714692493721308237020679933333354780844...
		

Crossrefs

Programs

  • Mathematica
    xi = 1/(1 + Sqrt[E]); P0[x_] := Log[x]^2/2 + Log[x] + PolyLog[2, x] - Pi^2/12 + 1; Join[{0}, RealDigits[P0[xi], 10, 101] // First]
  • Python
    from mpmath import *
    mp.dps=102
    xi=1/(1 + sqrt(e))
    C = log(xi)**2/2 + log(xi) + polylog(2, xi) - pi**2/12 + 1
    print([int(n) for n in list(str(C)[2:-1])]) # Indranil Ghosh, Jul 04 2017

Formula

(1/2)*log(1 + sqrt(e))^2 - log(1 + sqrt(e)) + Li_2(1/(1 + sqrt(e))) - Pi^2/12 + 1.

A248791 Decimal expansion of P_2(xi), the maximum limiting probability that a random n-permutation has exactly two cycles exceeding a given length.

Original entry on oeis.org

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

Views

Author

Jean-François Alcover, Oct 14 2014

Keywords

Examples

			0.0727887386608213733667186633181914296889295494487...
		

Crossrefs

Programs

  • Mathematica
    xi = 1/(1 + Sqrt[E]); P2[x_] := -Pi^2/12 + (1/2)*Log[x]^2 + PolyLog[2, x]; Join[{0}, RealDigits[P2[xi], 10, 100] // First]
  • Python
    from mpmath import *
    mp.dps=101
    xi=1/(1 + sqrt(e))
    C = -pi**2/12 + (1/2)*log(xi)**2 + polylog(2, xi)
    print([int(n) for n in list(str(C)[2:-1])]) # Indranil Ghosh, Jul 03 2017

Formula

-Pi^2/12 + (1/2)*log(1 + sqrt(e))^2 + Li_2(1/(1 + sqrt(e))).
Showing 1-5 of 5 results.