%I #2 Mar 30 2012 17:23:26
%S 1,0,-1,0,1,-1,0,1,-1,0,0,0,1,0,0,0,0,0,-1,1,0,-1,1,-1,1,-1,1,-1,0,0,
%T 1,-1,0,0,1,-1,0,0,0,1,-1,1,0,-1,1,-1,0,0,1,0,-1,0,0,0,1,-1,0,0,1,0,
%U -1,1,-1,0,1,0,-1,0,0,1,-1,0,1,0,-1,0,0,1,0,-1,0,1,0,-1,0,0,1,-1,1,-1,0,0,1
%N Signed-digit binary expansion of Pi/4
%o (PARI) r=Pi/4; for(k=0,99,if(abs(r)<1/2,d=0,d=sign(r));r=2*(r-d);print1(d,", "))
%Y Cf. A004601, A155996.
%K base,sign
%O 0,1
%A _Jaume Oliver Lafont_, Jan 23 2009
%E Corrected and cross-reference added by _Jaume Oliver Lafont_, Feb 05 2009