OFFSET
-1,1
COMMENTS
This constant is irrational. Its irrationality is a consequence of a more general theorem proved by Erdős (1969).
LINKS
Daniel Duverney and Yohei Tachiya, Refinement of the Chowla-Erdős method and linear independence of certain Lambert series, Forum Mathematicum, Vol. 31. No. 6 (2019), pp. 1557-1566, alternative link.
Paul Erdős, On the irrationality of certain series, Math. Student, Vol. 36 (1969), pp. 222-226.
EXAMPLE
0.06862364363141833337867373878285684762065359573504...
MATHEMATICA
RealDigits[Sum[1/(2^(Prime[k]^2) - 1), {k, 1, 100}], 10, 100][[1]]
PROG
(PARI) suminf(k=1, 1/(2^prime(k)^2-1)) \\ Michel Marcus, May 03 2020
CROSSREFS
KEYWORD
nonn,cons
AUTHOR
Amiram Eldar, May 03 2020
STATUS
approved