|
|
A272055
|
|
Decimal expansion of -1/(e^2 Ei(-1)), an increasing rooted tree enumeration constant associated with the Euler-Gompertz constant, where Ei is the exponential integral.
|
|
1
|
|
|
6, 1, 6, 8, 8, 7, 8, 4, 8, 2, 8, 0, 7, 2, 7, 0, 7, 1, 4, 4, 4, 9, 3, 8, 3, 4, 5, 6, 6, 2, 2, 8, 5, 4, 9, 3, 5, 2, 4, 9, 0, 0, 5, 6, 9, 3, 3, 1, 6, 8, 8, 1, 7, 8, 6, 5, 6, 6, 1, 0, 3, 3, 2, 3, 1, 9, 1, 4, 3, 7, 2, 4, 2, 5, 1, 5, 4, 7, 6, 7, 2, 7, 3, 0, 3, 3, 9, 8, 2, 5, 6, 0, 3, 1, 4, 9, 4, 8, 3, 4, 5, 1, 1
(list;
constant;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
0,1
|
|
REFERENCES
|
Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 5.6 Otter's tree enumeration constants, p. 303.
|
|
LINKS
|
F. Bergeron, Ph. Flajolet and B. Salvy, Varieties of Increasing Trees, Lecture Notes in Computer Science vol. 581, ed. J.-C. Raoult, Springer-Verlag, 1992, pp. 24-48.
|
|
FORMULA
|
Also equals -1 / (e^2 * (gamma - Sum_{n>=1} (-1)^(n-1)/(n*n!))), where gamma is the Euler-Mascheroni constant A001620.
|
|
EXAMPLE
|
0.61688784828072707144493834566228549352490056933168817865661...
|
|
MATHEMATICA
|
RealDigits[-1/(E^2*ExpIntegralEi[-1]), 10, 103][[1]]
|
|
PROG
|
(PARI) default(realprecision, 100); 1/(exp(2)*eint1(1)) \\ G. C. Greubel, Sep 07 2018
|
|
CROSSREFS
|
|
|
KEYWORD
|
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|