OFFSET
0
COMMENTS
arctanh(x) = x + x^3/3 + x^5/5 + x^7/7 + ...
LINKS
Wikipedia, p-adic number
EXAMPLE
arctanh(4) = ...0100000010101110111011111001111011000100.
PROG
(PARI) a(n) = lift(sum(i=0, (n-2)/4, Mod(4^(2*i+1)/(2*i+1), 2^(n+1))))\2^n
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Jianing Song, Aug 16 2019
STATUS
approved