login
A242000
Decimal expansion of delta = (1+alpha)/4, a constant appearing in Koecher's formula for Euler's gamma constant, where alpha is A065442, the Erdős-Borwein Constant.
1
6, 5, 1, 6, 7, 3, 7, 8, 8, 1, 0, 3, 8, 2, 2, 9, 4, 0, 9, 4, 5, 8, 2, 5, 3, 8, 0, 7, 9, 7, 7, 3, 1, 1, 4, 5, 1, 2, 0, 1, 4, 4, 9, 1, 7, 8, 7, 6, 4, 3, 9, 1, 0, 8, 9, 4, 4, 5, 1, 9, 8, 8, 8, 4, 2, 2, 8, 5, 4, 6, 0, 5, 1, 8, 5, 8, 7, 1, 6, 7, 2, 6, 4, 1, 4, 2, 7, 9, 5, 0, 4, 1, 7, 5, 3, 8, 8, 9, 3, 9, 7, 4
OFFSET
0,1
REFERENCES
Steven R. Finch, Mathematical Constants, Cambridge University Press, 2003, Section 5.14 Digital Search Tree Constants, p. 355.
LINKS
Eric Weisstein's Mathworld, Erdős-Borwein Constant
FORMULA
alpha = sum_{n>=1} 1/(2^n-1) = A065442 = 1.606695...
delta = (1+alpha)/4 = 0.65167...
gamma = delta - (1/2)*sum_{k>=2} (((-1)^k/((k-1)*k*(k+1)))*floor(log(k)/log(2))) = A001620 = 0.5772... (Koecher's formula).
EXAMPLE
0.6516737881038229409458253807977311451201449178764391089445...
MATHEMATICA
alpha = 1/2 - QPolyGamma[0, 1, 2]/Log[2]; delta = (1+alpha)/4; RealDigits[delta, 10, 102] // First
PROG
(PARI) default(realprecision, 100); (1 + suminf(k=1, 1/(2^k - 1)))/4 \\ G. C. Greubel, Sep 06 2018
CROSSREFS
Sequence in context: A216582 A340543 A177824 * A238181 A197517 A102079
KEYWORD
nonn,cons,easy
AUTHOR
STATUS
approved