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.

A084945 Decimal expansion of Golomb-Dickman constant.

Original entry on oeis.org

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

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Author

Eric W. Weisstein, Jun 13 2003

Keywords

Comments

The first 27 digits form a prime. - Jonathan Vos Post, Nov 12 2004
The first 1659 digits form a prime. - David Broadhurst, Apr 02 2010
The average number of digits in the largest prime factor of a random x-digit number is asymptotically x times this constant. - Charles R Greathouse IV, Jul 28 2015
Named after the American mathematician Solomon W. Golomb (1932 - 2016) and the Swedish actuary Karl Dickman (1861 - 1947). - Amiram Eldar, Aug 25 2020

Examples

			0.62432998854355087...
		

References

  • Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, pp. 284-287.

Crossrefs

Programs

  • Maple
    E1:= z-> int(exp(-t)/t, t=z..infinity):
    lambda:= int(exp(-x-E1(x)), x=0..infinity):
    s:= convert(evalf(lambda, 130), string):
    seq(parse(s[n+1]), n=1..120); # Alois P. Heinz, Nov 20 2011
  • Mathematica
    NIntegrate[Exp[LogIntegral[x]], {x, 0, 1}, WorkingPrecision->110, MaxRecursion->20]
  • PARI
    intnum(x=0,1-1e-9,exp(-eint1(-log(x)))) \\ Charles R Greathouse IV, Jul 28 2015
    
  • PARI
    default(realprecision, 103);
    limitnum(n->intnum(x=0, 1-1/n, exp(-eint1(-log(x))))) \\ Gheorghe Coserea, Sep 26 2018

Formula

From Amiram Eldar, Aug 25 2020: (Start)
Equals Integral_{x=0..1} exp(li(x)) dx, where li(x) is the logarithmic integral.
Equals Integral_{x=0..oo} exp(-x + Ei(-x)) dx, where Ei(x) is the exponential integral.
Equals Integral_{x=0..1} F(x/(1-x)) dx, where F(x) is the Dickman function. (End)

A174974 Numbers of decimal digits of the Golomb-Dickman constant A084945 that are prime.

Original entry on oeis.org

6, 27, 57, 60, 1659, 2508
Offset: 1

Views

Author

Eric W. Weisstein, Apr 02 2010

Keywords

Examples

			a(1) = 6 since 624329 is prime
a(2) = 27 since 624329988543550870992936383 is prime
		

Crossrefs

Extensions

a(5) from David J. Broadhurst, Apr 02 2010
a(6) from Eric W. Weisstein, Apr 03 2010
Showing 1-2 of 2 results.