A086309 - OEIS

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A086309

Decimal expansion of constant appearing in the expected number of comparisons for a successful digital tree search (negated).

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

(list; constant; graph; refs; listen; history; text; internal format)

OFFSET

0,1

REFERENCES

Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 5.14 Digital Search Tree Constants, p. 355.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 0..1000

Eric Weisstein's World of Mathematics, Tree Searching

FORMULA

3/2 + (gamma-1)/log(2) - alpha, where gamma is Euler's constant and alpha is the Erdős-Borwein constant (A065442). - Jean-François Alcover, Jul 29 2014, after Steven Finch

EXAMPLE

-0.7166440160273880204968086847847011827447940946...

MATHEMATICA

digits = 102; alpha = NSum[1/(2^k-1), {k, 1, 500}, NSumTerms -> 100, WorkingPrecision -> digits+10]; RealDigits[3/2 + (EulerGamma-1)/Log[2] - alpha, 10, digits] // First (* Jean-François Alcover, Jul 29 2014 *)

CROSSREFS

Cf. A065442, A086310.

Sequence in context: A176438 A092615 A199279 * A358187 A255888 A060625

Adjacent sequences: A086306 A086307 A086308 * A086310 A086311 A086312

KEYWORD

nonn,cons

AUTHOR

Eric W. Weisstein, Jul 15 2003

STATUS

approved