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A309752
Digits of the 2-adic integer arctan(2).
4
0, 1, 0, 1, 0, 0, 1, 1, 0, 1, 0, 0, 0, 1, 1, 1, 1, 1, 1, 0, 1, 0, 1, 1, 0, 1, 0, 1, 1, 1, 0, 1, 1, 0, 0, 1, 1, 0, 1, 0, 1, 0, 1, 1, 0, 1, 1, 1, 1, 0, 1, 1, 0, 0, 0, 0, 1, 1, 0, 1, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 0, 0, 1, 1, 1, 0, 0, 0, 0, 1, 0, 1, 0, 1, 1, 0, 1
OFFSET
0
COMMENTS
arctan(x) = x - x^3/3 + x^5/5 - x^7/7 + ...
FORMULA
a(n) = (A309751(n+1) - A309751(n))/2^n.
EXAMPLE
arctan(2) = ...0101100110111010110101111110001011001010.
PROG
(PARI) a(n) = lift(sum(i=0, (n-1)/2, Mod((-1)^i*2^(2*i+1)/(2*i+1), 2^(n+1))))\2^n
CROSSREFS
Sequence in context: A175992 A173922 A213676 * A209355 A141743 A268384
KEYWORD
nonn,base
AUTHOR
Jianing Song, Aug 15 2019
STATUS
approved