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.
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
Offset: 0
Examples
0.61688784828072707144493834566228549352490056933168817865661...
References
- Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 5.6 Otter's tree enumeration constants, p. 303.
Links
- G. C. Greubel, Table of n, a(n) for n = 0..10000
- 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.
- Eric Weisstein's MathWorld, Gompertz Constant
- Eric Weisstein's MathWorld, Exponential Integral
- Eric Weisstein's MathWorld, Rooted Tree
- Index entries for sequences related to mobiles
Programs
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Mathematica
RealDigits[-1/(E^2*ExpIntegralEi[-1]), 10, 103][[1]]
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PARI
default(realprecision, 100); 1/(exp(2)*eint1(1)) \\ G. C. Greubel, Sep 07 2018