%I #13 Jan 08 2024 09:02:46
%S 1,1,1,1,1,1,1,0,1,1,1,1,1,1,1,0,1,1,1,1,1,1,1,0,1,1,1,1,0,1,1,0,1,1,
%T 1,1,1,1,1,0,1,1,1,1,1,1,1,0,1,1,1,1,1,1,1,0,1,1,1,1,0,1,1,0,1,1,1,1,
%U 1,1,1,0,1,1,1,1,1,1,1,0,1,1,1,1,1,1,1,0,1,1,1,1,0,1,1,0,1,1,1
%N 0 iff n is of the form 4^a*(8k+7), otherwise 1.
%C 0 iff n is not the sum of three squares.
%H J.-P. Allouche and J. Shallit, <a href="https://www.cs.uwaterloo.ca/~shallit/Papers/as0.ps">The ring of k-regular sequences</a>, preprint.
%H J.-P. Allouche and J. Shallit, <a href="https://doi.org/10.1016/0304-3975(92)90001-V">The ring of k-regular sequences</a>, Theoretical Computer Sci., Vol. 98 (1992), pp. 163-197.
%H <a href="/index/Ar#2-automatic">Index entries for 2-automatic sequences</a>.
%Y 1's complement to A072401. Cf. A071377.
%K nonn
%O 0,1
%A _N. J. A. Sloane_, Jun 12 2002