

A068985


Decimal expansion of 1/e.


62



3, 6, 7, 8, 7, 9, 4, 4, 1, 1, 7, 1, 4, 4, 2, 3, 2, 1, 5, 9, 5, 5, 2, 3, 7, 7, 0, 1, 6, 1, 4, 6, 0, 8, 6, 7, 4, 4, 5, 8, 1, 1, 1, 3, 1, 0, 3, 1, 7, 6, 7, 8, 3, 4, 5, 0, 7, 8, 3, 6, 8, 0, 1, 6, 9, 7, 4, 6, 1, 4, 9, 5, 7, 4, 4, 8, 9, 9, 8, 0, 3, 3, 5, 7, 1, 4, 7, 2, 7, 4, 3, 4, 5, 9, 1, 9, 6, 4, 3, 7, 4, 6, 6, 2, 7
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OFFSET

0,1


COMMENTS

From the "derangements" problem: this is the probability that if a large number of people are given their hats at random, nobody gets his own hat.
Also, decimal expansion of cosh(1)sinh(1).  Mohammad K. Azarian, Aug 15 2006
Also, this is lim_{n>inf} P(n), where P(n) is the probability that a random rooted forest on [n] is a tree. See image from Wikipedia link.  Washington Bomfim, Nov 01 2010
Lim_{x>infinity} (1  1/x)^x = 1/e.  Arkadiusz Wesolowski, Feb 17 2012
Also, location of the minimum of x^x.  Stanislav Sykora, May 18 2012
Also, 1/e is the global minimum of x*log(x) at x = 1/e and the global minimum of x*e^x at x = 1.  Rick L. Shepherd, Jan 11 2014
Also, the asymptotic probability of success in the secretary problem (also known as the sultan's dowry problem).  Andrey Zabolotskiy, Sep 14 2019


REFERENCES

A. Hald, A History of Probability and Statistics and Their Applications Before 1750, Wiley, NY, 1990 (Chapter 19).
J. Harris, J. L. Hirst and M. Mossinghoff, Combinatorics and Graph Theory, Springer Science & Business Media, 2009, p. 161.
L. B. W. Jolley, Summation of Series, Dover (1961) eq (103) on page 20.
J. Riordan, An Introduction to Combinatorial Analysis, Wiley, 1958, p. 65.
M. Schroeder, Number Theory in Science and Communication, Springer Science & Business Media, 2008, ch. 9.5 Derangements.
W. D. Wallis and J. C. George, Introduction to Combinatorics, CRC Press, 2nd ed. 2016, theorem 5.2 (The Derangement Series).


LINKS

G. C. Greubel, Table of n, a(n) for n = 0..10000
Mohammad K. Azarian, An Expansion of e, Problem # B765, Fibonacci Quarterly, Vol. 32, No. 2, May 1994, p. 181. Solution appeared in Vol. 33, No. 4, Aug. 1995, p. 377.  Mohammad K. Azarian, Feb 08 2009
James Grime and Brady Haran, Derangements, Numberphile video, 2017.
Gérard P. Michon, Final Answers: InclusionExclusion
Eric Weisstein's World of Mathematics, Derangement
Eric Weisstein's World of Mathematics, Factorial Sums
Eric Weisstein's World of Mathematics, Spherical Bessel Function of the First Kind
Eric Weisstein's World of Mathematics, Sultan's Dowry Problem
Eric Weisstein's World of Mathematics, e
OEIS Wiki, Number of derangements
Index entries for transcendental numbers


FORMULA

Equals 2*(1/3! + 2/5! + 3/7! + ...). [Jolley]
Equals 1  Sum_{i >= 1} (1)^(i  1)/i!. [Michon]
Equals j_1(i)/i = cos(i) + i*sin(i), where j_1(z) is the spherical Bessel function of the first kind and i is the imaginary unit in C.  Stanislav Sykora, Jan 11 2017
Equals Sum_{i>=0} ((1)^i)/i!.  Maciej Kaniewski, Sep 10 2017
Equals Sum_(i>=0} ((1)^i)(i^2+1)/i!.  Maciej Kaniewski, Sep 12 2017
From Peter Bala, Oct 23 2019: (Start)
The series representation 1/e = Sum_{k >= 0} (1)^k/k! is the case n = 0 of the following series acceleration formulas:
1/e = n!*Sum_{k >= 0} (1)^k/(k!*R(n,k)*R(n,k+1)), n = 0,1,2,..., where R(n,x) = Sum_{k = 0..n} (1)^k*binomial(n,k)*k!*binomial(x,k) are the row polynomials of A094816. (End)
1/e = 1  Sum_{n >= 0} n!/(A(n)*A(n+1)), where A(n) = A000522(n).  Peter Bala, Nov 13 2019
Equals Integral_{x=0..1} x * sinh(x) dx.  Amiram Eldar, Aug 14 2020


EXAMPLE

1/e = 0.3678794411714423215955237701614608674458111310317678... = A135005/5.


MATHEMATICA

RealDigits[N[1/E, 6! ]][[1]] (* Vladimir Joseph Stephan Orlovsky, Jun 18 2009 *)


PROG

(PARI)
default(realprecision, 110);
exp(1) \\ Rick L. Shepherd, Jan 11 2014


CROSSREFS

Cf. A000166, A001113, A068996, A092553.
Cf. A059193.
Cf. asymptotic probabilities of success for other "nothing but the best" variants of the secretary problem: A325905, A242674, A246665.
Sequence in context: A003458 A133339 A112267 * A081391 A296484 A073850
Adjacent sequences: A068982 A068983 A068984 * A068986 A068987 A068988


KEYWORD

nonn,cons


AUTHOR

N. J. A. Sloane, Apr 08 2002


EXTENSIONS

More terms from Rick L. Shepherd, Jan 11 2014


STATUS

approved



