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A078888
Decimal expansion of Sum {n>=0} 1/7^(2^n).
8
1, 6, 3, 6, 8, 1, 9, 7, 2, 7, 1, 6, 8, 6, 8, 0, 1, 7, 9, 1, 1, 7, 2, 9, 7, 2, 5, 8, 9, 3, 9, 0, 9, 2, 0, 0, 6, 0, 5, 2, 4, 4, 8, 5, 4, 1, 5, 9, 3, 3, 6, 8, 2, 5, 3, 2, 7, 8, 6, 2, 2, 1, 0, 3, 5, 9, 7, 2, 5, 1, 1, 8, 5, 9, 2, 9, 2, 3, 5, 7, 5, 0, 2, 5, 1, 1, 7, 3, 9, 7, 8, 4, 0, 1, 2, 7, 2, 9, 4, 3, 8, 1, 8, 4, 7
OFFSET
0,2
LINKS
Aubrey J. Kempner, On Transcendental Numbers, Transactions of the American Mathematical Society, volume 17, number 4, October 1916, pages 476-482.
FORMULA
Equals -Sum_{k>=1} mu(2*k)/(7^k - 1), where mu is the Möbius function (A008683). - Amiram Eldar, Jul 12 2020
EXAMPLE
0.163681972716868017911...
MATHEMATICA
RealDigits[ N[ Sum[1/7^(2^n), {n, 0, Infinity}], 110]][[1]]
PROG
(PARI) suminf(n=0, 1/7^(2^n)) \\ Michel Marcus, Nov 11 2020
CROSSREFS
KEYWORD
cons,nonn
AUTHOR
Robert G. Wilson v, Dec 11 2002
STATUS
approved